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Networking Encyclopedia
Ethernet Topologies 5-4-3 rule: States that a thinnet network can combine as many as five cable segments connected by four repeaters. Only three segments can have stations attached, which leaves two segments untapped. 10Base2 Ethernet: Ethernet toplogy that has Data transfer rates of 10Mbps over baseband wire, and can carry a signal 185 meters; RG-58 coaxial cable and BNC connectors. 10Base5 Ethernet (standard Ethernet): A network toplolgy that transmits at 10 Mbps over a baseband wire and can carry a signal 500 meters (five 100-meter segments); Requires the use of a main bus cable; nodes on a 10Base5 Ethernet network are arranged in a physical bus. (pictures of physical network topolgies - use SnagIt) 10BaseFL: Ethernet network that typically ses fiber-optic cable to connect computers and repeaters. 100BaseX Ethernet (Fast Ethernet): An extension to the existing Ethernet standar, running on UTP Cat 5 data-grade cable and uses CSMA/CD in a star-wired bus toplogy, similar to 10BaseT in which all cables are attached to a hub. 10BaseT Ethernet: Ethernet network topology that uses UTP cable connections; Data transfer rate of 10Mbps. CAT 3 UTP cable required on 10BaseT Ethernet networks, and RJ-45 connectors. The max. length of a 10BaseT segment is 100 meters (328 feet). 100BaseFX Fast Ethernet: Data transfer rate of 100Mbps, fiber-optic cable and fiber-optic cable connectors, such as ST or SC connectors. 1000BaseT Gigabit Ethernet: Specifies a max. data transfer rate of 1 Gbps. Cat 5 UTP cable and RJ-45 connectors are typically used on 1000BaseT Ethernet networks. 100VG (Voice Grade) AnyLAN (100VGAnyLAN): An emerging networking technology that combines elements of both Ethernet and Token Ring. Access method: Set of rules that defines how a computer puts data onto the network cable and takes data from the cable. When data is moving on the network, access methods help to regulate the flow of network traffic. Acess permissions: Features that control access to sharing in Win NT Server. Permissions can be set fo the following access levels:
Activity Directory Users & Computers:In Win 2k, you can use Active Directory Users and Computers to manage user and group accounts. Win NT does not include the Active Directory User and Computers utility or the Active Directory Sites and Services Utility. Activity Sites & Services: You can use Active Directory Sites and Services in Win 2k to create and manage sites and to manage directory services. Address Resolution Protocol (ARP): TCP/IP uses ARP to resolve IP addresses to MAC addresses so that TCP/IP and Ethernet, or another Physical layer protocol, can interoperate. The arp command will not diplay the MAC address for the NIC in your Win 98 computer. Issue the arp -a command to view the ARP cache for the computer, which displays the IP address and its corresponding MAC address for all entries in the cache. Determines hardware MAC addresses that correspond to an IP address. Advanced program-to-program communication (APPC): A specification developed as part of IBMs SNA (Systems Network Architecture) model and designed to enable application programs running on different computers to communicate and exchange data directly. Agent: A program that performs a background task for a user and reports to the user when the task is done or when some expected event has taken place. American National Standards Institute (ANSI): Dedicated to the develpment of trade and communications standards. ANSI is the American representative to the ISO. American Wire Gauge (AWG): A standard that determines wire diameter. The diameter varies inversely to the gauge number. Amplifier: A device, such as a repeater or bridge, that amplifies or increases the power of electrical signals, allowing them to travel on additional cable segments at their original strength. Stenghtns signals that have been weakened by attenuation. Application Layer of the OSI Model: HTTP is an Application-layer protocol that uses the connection-oriented services of TCP, and TFTP is an Application-layer protocol that uses the connectionless services of UDP. AppleShare: Apple network architecture that is included in the Mac OS software. It is a collection of protocols that correspond to the OSI model. Thus network capabilities are built into every Mac AppleTalk: Protocol that supports LocalTalk, Ethernet (EtherTalk), and Token Ring (TokenTalk). AppleTalk filing protocol (AFP): Describes how files are stored and accessed on the network. Responsible for the Apple hierarchical filing structure of volumes, folders, and files and provides for file sharing between Macs and MS-DOS based computers. Provides interface for communication between AppleTalk and other network OSs, allowing Macs to be integrated into any network that uaes an OS that recognizes AFP. Application Programming Interface (API): A set of routines that an application program uses to request and carry out lower level services performed by the OS. Application Protocols: Protocols that work at the higher end of the OSI reference model, providing application-to-application interaction adn data exchange. Popular application protocols include:
ARCNET: Requires RG-62 coaxial cable. Also uses a token bus network access scheme that is similar to IEEE 802.4 Token Bus. American Standard Code for Information Interchange (ASCII): Coding scheme that assignes numeric values to letters, numbers, punctuation marks, and certain other characters. Enables compuers and computer programs to exchange a standardized system of information. Asynchronous Digital Subscriber Line (ADSL): Always-on digital subscriber line solution. ADSL provides faster download times than upload times. Usually cheaper than T1, comparable in price to ISDN, and more expensive than PSTN. Maximum of 12, 00 feet from telco's (CO) Central Office can offer an upload of at least 500 Kbps and a download transmission speed of at least 6.312 Mbps. The telco's CO requires DSL splitters and multiplexers to support DSL service. Asynchronous transfer mode (ATM): An advanced implementation of packet switching that provides high-speed data transmission rates to send fixed-size cells over broadband LANs or WANs. Cells are 53bytes-48bytes of data with five additional bytes of address. ATM accommodates voice, data, fax, real-time video, CD-quality audio, imaging, and multimegabit data transmissions. ATM uses switches as multiplexers to permit several computers to put data on a network smultaneously. Most commercial ATM boards transmit data at about 155 Mbps, but theoretically a rate of 1.2 gigabits per second is possible. Attachment User Interface (AUI): Connectors used to connect computers to 10Base 5 Ethernet networks. The connector used with standard Ethernet that often includes a cable running off the main, or backbone, coaxial cable. Also known as a DIX connector. Attenuation: The weakening or degrading (distorting_ of a transmitted signal as it travels farther from its points of origin. This could be a digital signal on a cable or the reduction in amplitude of an electrical signal, without the appreciable modification of the waveform. Usually measured in decibels. Attenuation of a signal transmitted over a long cable is corrected by a repeater, which amplifies and cleans up an incoming signal before sending it farther along the cable. Auditing: A process that tracks network activities by user accounts and a routine element of network security. Auditing can produce records of lsit users who have accessed - or attempted acces - specific resources; help administrators identify unauthorized activity; and track activities such as logon attempts, connection and disconnection from designated resources, changes made to files and directories, server events and modifications, password changes, and logon parameter changes. Authentication: Verification based on user name, passwords, and time and account restrictions.
Backbone: The main cable, aslo known as the trunk segment, from which transceiver cables connect to computers, repeaters, and bridges. Back end: In a client/server application, the part of the program that runs on the server. Backup: A duplicate copy of a program, a disk, or data, made to secure valuable files from loss. Backup domain controller (BDC): In a Win NT Server domain, a computer that receives a copy of the domain's security policy and domain database and authenticates network logons. It provides a backup if the PDC becomes unavailable. A domain is not required to have BDC, but it is recommended to have a BDC to back up the PDC. Bandwidth: In communications, the difference between the highest and lowest frequencies in a given range. Telephone accommodates a bandwidth of 300Hz, or the difference between the lowest (300Hz) and higherst (3300Hz) frequencies it can carry. In computer networks, greater bandwidth indicates faster or greater data-transfer capability. Basic Rate Interface - Integrated Services Digital Network (BRI-ISDN): Requires a special dedicated digital line. Only supports a maximum data transfer rate of 128 Kbps. BRI ISDN offers wo B channels and one D channel. The B channels on a BRI ISDN line each operate at 64 Kbps, and the D channel operates at 16 Kbps. The two B channels can be combined for a total data transmission rate of 128 Kbps. Barrel connector: A component that can connect two peices of cable to make a longer piece of cable. Baseband: A system used to transmit the encoded signals over cable. BAseband uses digital signaling over a single frequency. Signals flow in the form of discrete pulses of electricity of light. With baseband transmission, the entire communication-channel capacity is used to trnasmit a single data signal. Base I/O port: Specifies a channel through which information is transferred between a compute's hardware, such as the NIC, and its CPU. Base memory address: Defines the address of the location in a computer's memory (RAM) that is used by the NIC. Sometimes refered to as the RAM start address. BAUD: A measure of data-transmission speed named after the French engineer and telegrapher Jean-Maurice-Emile Baudot. It is a measure of the speed of oscillation of the sound wave on which a bit of data is carried over telephone lines. Because baud was originally used to measure the transmission speed of telegraph equiment, the term sometimes refers to the data-transmission speed of a modem. Baud Rate: Refers to the speed at which a modem can transmit data. (not the same as number of bits per second transmitted), baud rate actually measures the number of events, or signal changes, that occur in one second. Because one event can actually encode more than one bit in high-sp[eed digital communication, baud rate and bps are not always synonymous, and the latter is the more accurate term to apply to medems. For example, the 9600-baud modem that encodes four-bits per event actually operates at 2400 baud, but transmits at 9600 bps (2400 events times 4 bits per event), and thus should be called a 9600-bps modem. Beaconing: The process of signaling computers on a ring system that token passing has been interrupted by a serious error. All computers in an FDDI or Tekin Ring netwrok are responsible for monitoring the token-passing process. To isolate serious failures in the ring, FDI and Token Ring use beaconing in which a computer taht detects a fault sends a signal, called a beacon, onto the network. Teh computer continues to send the beacon until it notices a beacon from its upstream neghbor. This proces continues until the only downstream of the failure. When the beaconing computer finally receives its own beacon, it assumes the problem has been fixed and regenerates a token. Bind: To associate two peices of information with one another. Binding: A process that establishes the communication channel between a protocol driver and a NIC driver. BInary synchronous communications protocol (Bisync): A communications protocol developed by IBM. Bisync transmissions are encoded ineither ASCII or EBCDIC. Messages can be of any length and are sent in unitws called frames, optionally precded by a message hear\der. Because bisync uses synchronous transmission, oin which message elementws are separated by aspecific time intervfal, each frame is preceded and followed by special characers that enable the sending and receiving machnes to synchronize their clocks. Black out: occurs when all power is lost in the electric power lines, typically for an extended period of time. BNC: Connectors are used to connect computers to 10Base2 Ethernet networks. BNC T connector BNC barrel connector BNC terminator Boot-sector virus: A type of virus that resides in the first sector of a floppy disk or hard drive. When the computer is booted, the virus executes. In this common method or transmitting viruses from one floppy disk to another, the virus replicates itself onto the new drive each time a new disk is inserted and accessed. Bottleneck: A device or program that significantly degrades network perormance. Poor network performance results when a device uses noticeably more CPU time than it should, consumes too much of a resource, or lacks the capacity to handle the load. Potential botlenecks can be found in the CPU, memory, NIC, and other components. Bounce (see signal bounce) Bridge: A device that can divide a network into two segments. A network divided by a bridge appears to be a single network to devices and applications that operate at a higher level than the bridge. Normally a bridge is used to divide a network to optimize network traffic. Bridges can be used to increase the length or number of nodes for a network. Makes connections at the data-link layer of the OSI reference model. Broadband Integrated Services Digital Network (BISDN): A consultative committee for the CCITT that recommends definitions for voice, data, and video in the megabit-gigabit range. BISDN is also a single ISDN network that can handle voice, data, and video servies. BISDN works with an optical cable transport network called Synchronous Optical Network (SONET) and an ATM switching service. SMDS (Switched Multimegabit Data Services) is a BISDN service that offers high bandwidth to WANs. Broadband network: A type of LAN on which transmissions travel as analog (radio-frequency) signals over separate inbound and outbound channels. Devices on a broadband netwok are connected by coaxial or fiber-optic cable, and signal s flow across the physical medium in the form of electromagnetic or optical waves. A broadband system uses a large portion of the electromagnetic spectrum with a range of frequencies from 50Mbps to 600 Mbps. These networks can simultaneously accommodate TV, voice, data, and other servides over multiple transmission cahnnels. Broadcast storm: An event that occurs when there are so many broadcast messages on the network that they approach or supass the capacity of the netwrk bandwidth. This can happen when one computer on the network trnsmits a flood of frames saturating the network with traffic so it can no longer carry messages from any olther computer. Such a broadcast strom can shut down a network. Broater: a network component that combines the best qualities of a bridge and a router. CAn act as a router for one protocol and as a bridge for all the others. Can route selected routable protocols, bridge nonroutable protocols, and deliver more cost-effective and manageable internetworking than seaprate bridge and routers. Brown out: Occurs when the amount of power in electrical power lines drops for an extended period of time. Bus Topology: Byte: unit of information consisting of 8 bits.
Cable categories: The three major groups of cabling that connect the majority of networks: coaxial, twisted-pair, and fiber-optic cabling. Cache: A special memory subsystem or part of RAM in which frequently used data values are duplicated for quick access. A memory cache stores the contents of frequenctly accesed RAM locations and the addresses where these data iems are stored. When the processor references an address in memory, the cache checks to see whenteher ti holds that address. If it does hold the address, the data is returned to the aprocessor; if it does not, regular memory acdess occurs. A cache is useful when RAM accesses are slow as compared to the mircoprocdessor speed. Carrier-sense multiple access with collision avoidance (CSMA/CA): access method: An access method by which each computer signals its intent to transmit before it actually transmits data, thus avoiding possible transmission collisions. Carrier Sensing Multiple Access/Collision Detection (CSMA/CD): Network nodes can determine whether data is being transmitted on the network. Multiple access means that any node can transmit data when it determines that the network is free. Collision detection means that a node can sense when multiple nodes have simultaneously transmitted data, a situation called a data collision. A data collision can corrupt data and a node on a CSMA/CD network can resend data that has been corrupted in a data collision. CAT 5 UTP: Unshielded twisted-pair cable has eight strnads of 22-gauge or 24-gauge copper wire. Each strand of copper wire in a CAT 5 UTP cable is contained in a protective plastic sheath. The strands of wire are grouped into pairs, and each pair is twisted together. The four twisted pairs in a CAT 5 UTP cable are contained in a flexable plastic sheath. Used in several implementations of Ethernet, including 10BaseT Ethernet, 100BaseTX Fast Ethernet and 1000BaseT Gigabit Ethernet. Certificat Authorities (CAs): maintain digital certificates. A DS includes several fields, such as a serial number, a signature algorithm ID number and the period that the certificate will be valid. A CA does not typically require a user's actual signature to be placed in a digital certificate, and a user' actual signature is not required by a digital signature. Channel Service Unit/Data Service Unit (CSU/DSU): Used to directly connect a LAN to a telephone company's digital data service (DDS) line. You can also use a CSU/DSU to directly connect a LAN to a frame relay network. A CSU/DSU is a combination device that performs the functions of a CSU and a DSU. A CSU terminates a telephone devices: routers, multiplexers and switches. A DSU converts signals from the LAN to signals that are compatible with frame relay or the digital line to which a LAN is connected. A DSU also establishes and maintains a connection with the digital Dervice. ON a network that uses separate CSU and DSU hardware devices, the DTE connects to the CSU, the CSU connects to the DSU and the DSU connect to the DDS. On a network that uses a CSU/DSU integrated device, the DTE is connected to the CSU/DSU and the CSU/DSU is connected to the telco DDS line. Used to connect each of the routers to a T1 line. CSU/DSU devices will transmit the data provided by the routers on the T1 line. Cable modem: Used to connect computers to broadband cable networks. Cellular Digital Packet Data (CDPD): A comm. standard that uses very fast technology, similar to that of cellular telephones, to offer computer data transmissions over existing analog voice networks between voice calls, when the system is not occupied with voice communication. Central file server: A network in which specific computers take on the role of sever with other computers on the network sharing the resources. Cladding: The concentric layer of glas that surrounds the extremely thin, cylindrical glass core in fiber-optic cable. Class IP addresss: The class of an IP address can be identified by the first octet of the address. Class A IP Address: 1st octet ranges from 1 through 126. 1st octet equals network address, while the remaining three octets form the host address. (ie. 125.10.12.220 or 110.0.0.1) Class B IP Address: Class C IP Address: 1st otect ranges from 192 through 223. The 1st three octets form the network address, and the fourth octet represents the host address. (ie. 221.34.8.230). The default subnet mask for a Class C IP address is 255.255.255.0. Class DIP Address: 1st octet ranges from 224 through 239. Used for multicasting. Class undefined: ranges from 220 through 254. Reserved for testing. Client Services for NetWare (CSNW): can be installed on a Windows NT 40 computer to enable the computer to gain acces to resources on Novell NetWare 4.11 servers. Comite Consultatif Internationale de Telegraphie et Telephonie (CCITT): An organization based in Geneva, Switzerland, and established as part of the United Nations International Telecommunications Union (ITU). The CCITT recommends use of communication standards that are recognized throughout the world. Protocols established by the CCITT are applied to modems, networks, and facsimile transmission. Commercial COMSEC Endorsement Program (CCEP): A data-encyption standard introduced by the National Security Agency. Vendors who have the proper security clearance can join CCEP and be authorized to incorporate classified algorithms into communications systems. Companion virus: A virus that uses the name of a real program, but has a different file extension from that of the program itself. The virus is activated when its companion program is opened. The companion virus uses a .COM file extension, which overrides the .EXE file extension and activates the virus. Concentrator: A network physical-layer device that serves as a central connection for other network devices. Connectionless communications: Do not provide flow control or data reception acknowledgement, and tend to be faster than connection-oriented communications. Contention: Competition among stations on a network for the opportunity to use a communication line or network resource. Two or more computers attempt to transmit over the same cable at the same time, thus causing a collision on the cable. Such a syustem needs regulation to eliminate data collisions on the cable which can destroy data and bring network traffic to a halt. Core: In coaxial cable, the innermost part of the cable that carries the electronic signals when make up the data. It can be solid (usually copper) or stranded. In fiber-optic cable, digital data signals travel through an extremely thin cylindrical glass core surrounded by clading. Crossover cable: A patch cable in which one connector's receivieng pins are connected to the other connector's sending pins and vice versa. You should use a CAT 5 UTP crossover cable to connect two hubs on a 100BaseT4 network. Crosstalk: Signal overflow from an adjacent wire. (ie. faint signal of another conversion on a telephone wire) Cyclick redundancy check (CRC): A form of error checking in transmitting data. The sending packet includes a number produced by a mathematical calculation made at te transmission source. WHen the packet arrives at its destination, the calculation is redone. If the two figures are the same, this indicates that the data in the packet has remained stable. If the calculation at the destination differs from the calculation at the source, this indicates that the data has changed during the transmission. In that case, the CRC routine signals the source computer to retransmit the data.
Data frmaes: Logical, structured packages in which data can be placed. Data being transmitted is segmented into small units and combined with control info such as mesage start and message end indicators. Each package of information is transmitted as a single unit, called a frame. The data-link layer packages raw bits fromt eh physical layer into data frames. The exact format of the frame used by the network deopends on the topology. Data Link-layer protocols: Database management system (DBMS): A layer of software between the physical database and the user. The DBMS manages all requests for data-base action from the user, uncluding keeping track of the pbysical details of ile locations and formats, indexing schemes, and so on. AIn addition, a DBMS permits centralized control of security and data integrity requirements.Data communications Equipment (DCE): One of two types of hardware connected by an RS-232 serial connection, the other being a DTE device. ADCE device takes input signal in some way before sending it to the actual recipient. For example, an external modem is a DCE device that acdcepts data from a microcomputer (DTE), modulates it, then sends the data along a telephone connection. In communication, an RS-232 DCE device receives data over line 2 and transmits over line 3. In contrast, a DTE device receives over line 3 and transmits over line 2. DECnet: Digital Equipment Corporation hardware and software products that implement the Digital Network Architecture (DNS). DECnet defines communication networks over Ethernet LANs, FDDI MANMs, and WANs that use private or public data transmission facilities. It can use TCP/IP and OSI protocols as well as Digital's DECnet protocols. Dedicated server: A computer on a network that functions only as a server and is not also used as a client. Data Encryption Standard (DES): Was developed at MIT to securely authenticate network users. Developed by U.S. government in the early 1970s to encryp;t government documents. DES uses a 56-bit encryption key. A stronger version of DES, know as Triple DES, uses a 168-bit encryption key. Data Terminal Equipment (DTE): According to the RS-232 hardware standard, a device, such as a microcomputer or a terminal, that has the ability to transmit info in digital form over cable or a communication line. A DTE is one of two types of hardware connected by an RS-232 seerial connection, the other being a DCE device, such as a modem, that normally connects the DTE to the communication line itself. In communication, an RS-232 DTE device transmits data over line 2 and receives it over line 3. A DCE receives over line 2 and transmits over line 3. Data Stream: An undifferentiated, byte =-by-byte flow of data. DB connector: A connector that facilitates parallel input and output. The initals DB stand for data bus. The numbers which follow DB indicate the number of wires within the connector. A DB-15 connector has 15 pins and supports up to 15 lines, each of which can connect to a pin on the connector; a DB-25 connector has 25 of each. Digital Signature: Requires a public key, a private key and a digital certificate. Public key/private key pair is used in asymmetric encryption, which is also referred to as public key encryption. Digital voltmeter (DVM): A basic, all-purpose electronic measuring tool. Indicates the amount of voltage passing through resistance, in network cable testing, voltmetes measure continuity to determine if a cable is able to carry current. Dual inline package switch (DIP): One or more small rocker or sliding switches that can be set to one of two states - closed or open - to control options on a circuit board. Dynamic Host Configuration Procol (DHCP): automatically assigns IP settings to a computer, such as IP address, subnet mask and default gateway. Direct memory access (DMA): Memory access that does not involve the CPU, frequently employed for data transfer directly between memory and an "intelligent" peripheral device such as a disk drive. Direct memory access (DMA) channel: A channel for direct memory access that does not involve the CPU, providing data transfer directly between memory and a disk drive. Disk mirroring: A technique, also known as disk duplicating, in which all or part of a hard disk is duplicated onto one or more hard disks, each of which ideally is attached to its own controller. With disk mirroring, any change made to the original disk is simultaneously made to the other disks. Disk mirroring is used in situations in which a backup copy of current data must be maintained at all times. Disk striping: Divides data into 64K blocks and spreads it equally in a fixed rate and order amoung all disk in an array. However, disk striping does not provide any fault tolerance because there is no data redundancy. If any partition in the set fails, all data is lost. DIX (Digital, Intel, Xerox) connector: The connector used with standard Ethernet that often includes a cable running off the main, or backbone, coaxial cable. Also known as an AUI connector. DNS: A TCP/IP service that resolves domain names to IP addresses. you can use nslookup command on a Win NT computer to troubleshoot problem with DNS on a TCP/IP network. Domain: For Microsoft networking, a collection of computers and users that share a common database and security policy that are stored on a Win NT Server domain controller. Each domain has a unique name. Domain controller: The Win NT Server-based computer that authenticates domain logons and maintains the security policy and master database for a domain. DDS Lines: Telephone companies offer several different types, including T1 lines and T3 lines
T1 Lines = double ended arrows Domain Name System (DNS): Q Name resolution system for the Internet? Downtime: The amount of time a computer system or associated hardware remains nonfunctioning. Driver: A software component that permits a computer system to communicate with a device. In most cases, the driver also manipulates the hardware in order to transmit the data to the device. DSL:
DSL Splitter: Separates the voice signed from the data signal. The voice signal is sent to standard telephone servioce and the data signal is sent to an ADSL multiplexer, which sends multiple signals on an ATM connection through the Internet. If the ADSL splitter at the CO is malfunctioning or not properly configured, then you might not be able to send and receive data or voice communications over the ADSL line. Dual shielded cable: Cable that contains one layer of foil and insulation and one layer of braided metal shielding. Dumb terminal: A device used for obtaining or entering data on a network that does not contain any "intelligence" or processing power provided by a CPU. Duplex transmission: Also called full-duplex transmission. Communication that takes place simultaneously, in both directions, between the sender and receiver. Electrostatic Discharge (ESD): Occurs when static electricity jumps from an object with a higher electrical charge to an object with a lower electrical charge. Electromagnetic Interference (EMI): Can occur near sources of strong magnetic fields, such as electrical generators and transformers. Transformers in fluorescent lighting sytems are a common cause of network communications problems. STP and coaxial cable are not as susceptible to EMI, but still can be affected by EMI. Install fiber-optic cable near sources of strong magnetic fields because fiber-optic cable is immune to EMI. Fast Ethernet: or 100BaseT. operates at 100 Mbps and uses the star topology. Fiber-optic: Has a central silica glass or
plastic core that is surrounded by a layer of glass known as cladding,
which refracts light back into the core. The cladding is surrounded
by a protective layer, which is usually constructed of plastic.
1000BaseSX Gigabit Ethernet and 10Base FB Ethernet, also use fiber-optic
cable. File and Print Services for NetWare (FPNW): Can install on Win NT 4.0 computers to enable NetWare clients to gain access to files and printers hosted by Win NT Server 4 computers. Firewall/Proxy Server: Firewall slution normally includes packet-filtering technology, which can help protect a private network by allowing or denying data packets to enter and exit the network based on certain configurable criteria, such as the TCP port and destination domain of data packets. Firewire: Should be installed between the Internet and your company's private network. Can provide packet-filtering services. Data packets can be allowed or denied entery in to or out of a network based on several critera, including the TCP and the IP address of the sending host. Configure the firewall to deny access to packets from the Internet that are sent through TCP port 80, which is the well-known TCP port for HTTP messages. FOX: Sometimes referred to as a tone generato, and a hound is sometimes referred to as a tone locator. You can use a fox and a hound to locate the end of a cable. You connect a fox to one end of a cable, and the fox generates a tone. Then, you can use the hound to find the tone that the fox is generating on the other end of the cable. Thus, a fox and hound can be used to trace a cable. Frame Relay: Evolved from Integrated Services Digital Network (ISDN), which is a digital connection service offered by many telephone campanies. Frame relay is a packet switching technology that is used to connect LANs in a multi-point WAN. Frame relay establishes either switched virtual circuits (SVCs) or permanent virtual circuits (PVCs) between LANs though the frame relay cloud. Permanent virtual circuits are always on. Frame relay does not require a dedicated line as a T-carrier does. Instad, LANs are connected to a frame relay cloud and virtual circuits are established between LANs in a WAN. FTP: Uses ports 20 and 21. HTTPS and FTP are not used by e-mail clients to download messages from e-mail servers. Fully Qualified Domain Name (FQDN): (ie.server1.geotrek.com)
Gigabit Ethernet: Group of standards that define Ethernet networks that can transfer data at 1 gigabit per second. Sometimes referred to as 1000BaseX. The 1000BaseLX and the 1000BaseSX Gigabit Ethernet standards are implemented on fiber-optic cable. The 1000Base CX and the 1000BaseT Ethernet standards are implemented on copper cable. HOSTS file: This or the Domain Name System
(DNS) service must be used on Win NT TCP/IP network in order for
host names to be resolved to IP addresses. Must be manually configured
and updated, should be located on each network computer in order
for name resolution to be performed. The HOSTS file is stored in
the folder C:\WInnt\system32\drivers\etc. DNS provides a centralized
database of host name-to-IP address resolutions on a TCP/IP/ network.
If the DNS system is used on a network, then only the DNS servers
need to be updated when host names or IP addresses ae modified,
added or deleted. Hypertext Transfer Protocol Secure (HTTPS): Hub: a concentration point for network connections on a star-wired Ethernet LAN. Commonly used on networks that use unshielded twisted-pair (UTP), such as 10BaseT, 100BaseTX and 100BaseT4 networks. Most hubs use RJ-45 connectors, but combo hubs, have other connectors such as BNC and AUI. Used in star topolgy. Usually have LEDs that indicate network activity and connection status of connected workstations. IEEE 802.3 Standard: Describes Carrier Sense Multiple Access with Collision Detection (CSMA/CD), which is the network access method used on Ethernet networks. Defines Logical Link Control (LLC), which defines how the LLC sublayer of the Data Link layer of the OSI model operates. IEEE 802.5 Standard: Defines Token Ring networks. Token Ring networks use a logical ring topology and a token passing scheme to enable computers on the network to transmit data. Only the computer with the token, which is a small data packet, can transmit data on a Token Ring network. IEEE 802.11 Standard: Defines wireless LANs. Wireless networking enables computers to access a LAN without being connected to a LAN by a physical cable. Some wireless networks support satellite and infrared communications. Various wireless communication standards exist that define different sped and equipment for LANs, such as the 802.11a standard and the 802.11b standard. Internet Mail Access Protocol 4 (IMAP4): IBM 8228 MAU: Uses a Token Ring network to connect clients. If using only one MAU connect clients only to the user ports on the MAU. The ring-in/out ports are used to connect multiple MAUs. Using two MAUs, connect the ring-out/port on the 1st MAU to the ring-in port on the second MAU. For fault tolerance, you can connect a second cable from the ring-out port on the 2nd MAU to the ring-in port on the first MAU. Internet Protocol version 6 addresses (IPv6): Developed to replace IPv4 because IPv4 does not provide enough address space for the burgeoning internet. In the preferred text representation, an IPv6 address is a series of eight blocks of hexadecimal numbers. Each block can contain up to four hexadedimal numbers. The number blocks are separated by colon (:) characters. In eachnumber block, leading zeros do not need to be represented. (A:1:1::12.200.220.101, FEDC:BA09:87:6543:21:0:EFD:C, AAAA:9991:100A:0:210c Internet Protocol Security (IPSec): Used to encrypt the data packets on the network that you administer. IPSec can encrypt data packets transported on a TCP/IP network by using either tunnel mode or transport mode. In transport mode,kl IPSec encrypts only the part of an IP data packet used by the Transport layer. In tunnel mode, IPSec encrypts entire IP packets. IPSec uses several technologies to encrypt data, including the following: Diffie-Helman key exchange, Data Encryption Standard (DES), bulk encryption and digital certificates. Internet Protocol (IP): Is used to provide network addresses for hosts on the Internet and on private TCP/IP networks. Also used to provide internetwork routing on a TCP/IP network. IP is a connectionless protocol in the TCP/IP protocol suite. Operates at the Network layer of the OSI model and provides routing and addressing services for nodes on a network. IPX Protocol: The protocol that provides connectionless communications services, routing and network addressing for computers on an IPX/SPX network. The SPX protocol provides connection-oriented communications for computers on an IPX/SPX network. IPX is a connectionless protocol in the IPX/SPX protocol suite. Operates at Network layer of the OSI model and provides routing and addressing services for nodes on a network. IMAP4: Requires port 143 for communications Internetwork Packet Exchange/Sequenced Packet Exchange (IPX/SPX): network communications protocol is native to the Novel NetWare 4.11 operating system. Portion of the address after the colon character is the media access control (MAC) address for the network interface card (NIC) to which the IPX address is assigned. (00003344:96482412EFBA) Internet Printing Protocol (IPP): Can be used to send documents through the Internet for printing on a remote computer that is connected to the Internet. (ie. from london to tookyo) IP Proxy: Provides Network Address Translation (NAT); An IP proxy is usually installed between a private network and public network, such as the Internet. An IP proxy changes the IP addresses in data packets sent from the rquesting hosts on the private network to its IP address. All requests from the private network seem as though they originate from the IP proxy. An IP proxy that uses NAT can hide the addressing scheme used on a network, which can protect an internal network from malicious users. IRQ 1: Reserved for the keyboard. IRQ 3: Usually assigned to the secondary serial port, associated with CIM2 and COM4. IRQ 5: Typically used by either a secondary parallel port or a sound card. IRQ 6: Reserved for the floppy disk controller. IRQ 7: Reserved for the floppy disk controller, or local printer. IRQ12: sometimes used for PS/2 mouse. I/O port: A data channel that a hardware device and the CPU use to exchange data. Integrated Services Digital Network (ISDN): Provides an always-on digital connection to the telephone company. Tends to be faster and more expensive than PSTN. Basic Rate ISDN tends to be less expensive than ADSL and T1. ISDN Terminal Adapter: Sometimes incorrectly referred to as an ISDN modem. You cannot use an ISDN terminal adapter to directly connect a computer to a 100BaseTX Ethernet LAN. Kerberos: Uses ASs and TGSs to provide network
authentication. The Kerberos authentication protocol has been implemented
in the Windows 2000 OS and on several versions of the UNIX OS, including
FreeBSD. Kerveros is an authentication protocol based on Data Encryption
Standard (DES) that was developed at MIT to securely authenticate
network users. Layer 2 Tunneling Protocol (L2TP): Use with ISec to create avirtual private network VPN through the Internet. Creates a secure private tunnel through a Point-to-Point Protocol (PPP) connection on the Internet, through which VPN communications can be sent. Can create tunnels through TCP/IP, X.25, Frame Relay and Asynchronous Transfer Mode (ATM) networks. Layer 3 Switch: Device that operates at the Data Link layer and the Network layer of the OSI model and provides the functionality, such as data pipelining and virtual LANs (VLANs), of a standard Layer 2 switch. The Network layer of the OSI model is sometimes referred to as Layer 3, and the Data Link layer is sometimes referred to as Layer 2. A Layer 3 switch does not operate at the Physical layer of the OSI model. Line Printer Queue (LPQ): Utility to view the print jobs waiting to be printed on a UNIX print server. Also used to view print jobs in Queue on a UNIX print server. Line Printer Daemon (LPD): UNIX and Linux use this to receive print jobs and spool print jobs for printing. Line Printer Remote (LPR): Clients use this to send print jobs to UNIX and Linux print servers. Logical Link Control (LLC): The LLC sublayer of the Data Link layer of the OSI model interfaces with the Network layer above it and the Media Access Control (MAC) sublayer below it. The MAC sublayer handles physical addressing and interfaces with the LLC sublayer above it and the Physical layer of the OSI model below it. Loopback plug: Connects a NICs sending pins with its receiving pins. To test NIC communications, you should connect the loopback plug to the NIC, then use the NIC's diagnostic software to send data from the NIC's sending pins to its receiving pins. LMHOSTS : A slat-text file that contains NetBIOS name to IP address resolutions. Each computer on a Windows NT 4.0 network that uses LMHOSTS name resolution must have an LMHOSTS file, which must be manually updated when changes are made to NetTIOS name-to-IP address resolution system. Maintenance Wizard in NT: A tool that is used to schedule maintenance tasks in Win 98 and Me. You cannot use this in Win NT to manage users and groups. MAC Address: 12-digit hexadecimal number. Blocks of two digits each are usually separated by dash (-) characters. Assigned to each NIC. (12-34-56-78-90-AB) MAU: central connection point on a Token ring network. Media Access Control (MAC) Address: Operates
at the Physical layer of the OSI model. A unique, 480bit number
that is built into a NIC that connects to an Ethernet network. A
MAC address is divided into six octets, each of which represents
8-bits of the address as a two-digit hexadecimal number. 1st three
octets of a MAC address are assigned by the Institute of Electrical
and Electronics Engineers (IEEE) to each NIC manufacturer; these
three octets uniquely identify each NIC manufacturer. 08-00-09 = Hewlett-Packard Mesh topology: All computers are connected to every other computer on the network. To add a workstation you would have to add a connection to every existing computer in the network and directly connect the new computer to the 100 existing computers. In practice, full mesh networks do not typically exceed more than four or five nodes. Modem: Refers to modulator/demodulator. Enables a computer to transmit digital data over the analog Plain Old Telephone System (POTS). Exterminal modem typically has an RS-232 connector that connects to the DTE, such as a computer and an RJ-11 connector that connects through a standard telephone jack to the POTS local loop. The modem translates data send betwen POTS and the DTE. MS-DOS Commands: arp command: ipconfig/all: nslookup: winipcfg netstat: ping computername tracert : Windos dnsname command to determine the route a data packet takes as it travels through a TCP/IP internetwork. The dnsname variable is the Domain Name System (DNS) name of a computer in a TCP/IP network. (example of a DNS name: www.dropthescience.com) You can use the tracert and ping commands with various switches and variables to determine the route a packet takes through a TCP/IP network. nbstat -r : Used to troubleshoot the automatic NetBIOS name resolution problems on win 98,ME, 2000. You can use this to view WINS statistics in order to determine the number of NetBIOS name resolutions on a computer. If the number of name resolution is zero, then you can assume that there is a problem with a computer's WINS configuration. Multimode fiber-optic cable: Constructed with a 62.5-um core and 125-um cladding. Often referred to as 62.5/125 cable. 100BaseFX Ethernet network that is implemented on multimode fiber-optic cable cam support a maximum cable segment length of up to 2 kilometers.
NetWare for Macintosh (NFM): Network Access Server (NAS): Receives the incoming call will generate authentication request packets. A dial-up client dials in to a modem pool, which is connected to a NAS. The NAS collects authentication informationa frm the dial-up client, such as the username and password. The NAS is then connected to the RADIUS server, whcih contains authentication information for all the dial-up clients that dial in to the network. The connection between a NAS and the RADIUS server can use any of a variety of protocols, including TCP/IP, frame relay and ATM. The NAS sends the authentication request packet to the RADIUS server, which compares the credentials in the packet with its database of authentication credentials. The RADIUS server then sends the NAS an allow message or a deny message. If the NAS receives an allow message, then the dial-up client is allowed to gain access to network resoruces. If the NAS receives a deny message, then the dial-up client is not allowed to gain access to network resources. Network layer of OSI. Responsible for logical network addressing and routing. Protocols such as IPX. NetBEUI and IP operate at the Network layer. NAT: Process of changing the IP addresses in data packets is sometimes referred to as NAT. Hubs, MAUs and switches do not normally provide NAT. By using NAT, internal IP addresses can be used on network hosts, and NAT can translate those internal IP addresses into public IP addresses that can be used on the Internet. NAT is often used on a firewall to hide the addressing scheme that is used on an internal network. Because packets are re-addressed by NAT on the firewall and then sent to the Internet, they appear to have originated from a host that is not on the internal network. Thus, NAT can be used to hide internal host addresses from malicious users on the Internet. Novell Directory Services (NDS): Used in Novell NetWare 4.2 to gain access to WAN resources. Uses partitions for load balancing and fault tolerance. Earlier versions than 4.0 of Novell NetWare uses Novell Bindery to gain access to and administer network resources. The Bindery service only allows the management of configurations on the server that the netwrk administrator is currently using. Network Driver Interface Specification (NDIS) version 5: Normally used on Win 98 and Win 2000 computers. NDIS is a standard developed jointly by Microsoft and 3Com that simplifies the development of network interface card (NIC) drivers. NDIS is a library of programming code that provides a common interface between NIC drivers and network communications protocols, such as TCP/IP. If this library becomes corrupt, then the computer will probably not be able to communicate at all over a network. Network ID: Network Interface Card: Can often be assigned interrupt request (IRQ) 3 or 5. Network Address: Netowrk Interface Card (NIC): Operates at the Physical layer and the Data Link layer of the Open Systems Interconnection (OSI) model. Used to directly connect a computer to a LAN. Network News Transfer Protocol (NNTP): The protocol in the Transmission Control Protocol/Internet Protocol (TCP/PIP) protocol suite that transmits network news messages on the USENET network. NNTP can also be used to transfer network news articles on private TCP/IP networks. NWLink: The Microsoft implementation of the Internetwork Packet Exchange/Sequenced Packet Exchange (IPX/SPX) network communications protocol, on the Win NT Workstation 4 computer. IPX/SPX network protocol is native to NetWare 4.11; thus, this is the network comm. protocol that is being used on the network. NetBEUI: Is not a routable protocol. NeBEUI allws computers to communicate with each other that are on the same subnet, but not on the internet. Novell Directory Service (NDS): Directory service used on Novell NetWare networks that use Novell NetWare version 4 or later. An administer can use NDS to organize all network resources on a Novell NetWare network into a hierarchical structure called a NDS tree. NDS can be used to browse the resources on an entire Novell NetWare network. Versions before 4.0 support the directory service known as the bindery. The bindery represents only the resources on a single server; thus, the bindery can only be used to browse through the resources on a single Novell NetWare server. Novel NetWare 4.11 N.O.S.: Uses native network protocol IPX/SPX. Novell derived the IPX/SPX protocol from the earlier Xerox Network System (XNS). IPX/SPX is considered a legacy network protocol. Novell NetWare 5.x uses Transmission Control Protocol/Internet Protocol (TCP/IP) as a default protocol, but still supports IPX/SPX. Network Operating System (N.O.S.): Novell NetWare, Win NT 4.0 and Win 2000. All support the IPX/SPX network protocol. NetBIIOS Enhanced User Interface (NetBEUI) protocol is nativley supported by Microsoft OSs, and TCP/IP is native to UNIX, Linux and Microsoft Win 2000 OSs. Passwords: A stronge password contains uppercase and lowercase letters, symbols and numerals. (ie. bluE2#turTle) Generally, numeral, symbol and case changes should be embedded in a password to make a password stronger. Physical Layer of the OSI Model: Defines how data bits are translated into energy pulses that are sent over network cabling media. Aslo defines netowrk topologies, such as the ring, bus and mesh topologies. Other devices, such as hubs, transceivers and repeaters, also operate at the Physical layer of the OSI model. Post Office Protocol version 3 (POP3): Uses TCP port 110 to transmit data. Used by Outlook, Eudora, and other email clients. Power sag: Occurs when the amount of power in electrical power lines drops for a short period of time. Can cause intermittent problems, such as spontaneously rebooting computers, but power sags are unlikely to damage the circuits in a circuit board. Power spikes/power surges: Increases in the amount of power in electrical power lines above the normal level of power, can damage electrical circuits, such as a NIC. Public Key Encryption: A user share s the public key. Other users use the public key to encrypt files, and the original user can ue the private key to decrypt files that are encrypted with the public key Public key cryptography: A computer such as a server has a private key that is kept secret and a public key that is shared with the public. When a Web client contacts a Web server for an SSL session, the Web server sends the Web client its certificate, which contains the server's public key. the Web browser can contact a cerfificate authority to determine whether the certificate and the public key are authentic. After the Web client authenticates the server's certificate, the cleint encryptes a message and sends it ack to the server. Teh server then authenticates the client and the server negotiate an encryption algorithm, such as RSA or DES, to be used during the session. After the encryption algorithm is negotiated, messages on the session can be encrypted. Primary Rate Interface (PRI) Integrated Services Digital Network (ISDN): provides 23 Bearer (B) channels. Each B channel in a PRI ISDN connection can carry voice or data transmissions and operates at 64Kbps. A PRI ISDN channel also provides a single 64Kbps Delta (D) channel. The D channel carries signaling and control information for the PRI ISDN connection. If all of the data channels in a PRI ISDN connection are combined, then they can provide a max data transfer rate of 1.544 Mbps, which is comparable to the 1.544Mbps data transfer rate of a T1 line. Note that the end of an ISDN connection can be no more than 18, 00 feet from the centrol office of the telephone company. A telephone company is often referred to as a telco, and a telephone company's central office is sometimes referred to as a CO. Private key: only know to the owner. A digital certificate identifies a specific user as the owner of a public key/private key pair. Public Switched Telephone Network (PSTN): Typically the cheapest way to connect networks in aWAN when the telephonce connection does not cross international borders. Because it is a dial-up network, computers are not constantly connected to it. PSTN is the slowest of the listed WAN solutions. Redundant Array of Independent Disks (RAID 5): Requires at least three hard disks. If one fails in the array, then the data that was stored on the disk can be reconstructed from parity information on the operational disks in the array. Radio Frequency interference (RFI): occurs near sources of high power radio transmissions. TV stations, radio stations, cellular telephones and CB radios can be sources of RFI. RFI can cause network communications problems, and intermittent computer problems such as spontaneously rebooting computers and data errors. Does not usually damage circuit boards or microchips. Ring Topolgy: You must maintain a logical ring of computers. Difficultiy of maintaining a ring network is directly proportional to the size of the network. RJ-45 crossover cable: Sending pin 1 is connected to receiving pin 3 and sending pin 2 is connected to receiving pin 6. RG-58: ThinNet is mplemented using this coaxial cable standard. ThinNet sometimes referred to as 10Base2Ethernet. RG-62: RG-8: Refers to a general family of 50-ohm large-diameter coaxial cable that is used for many electronic aplications. Designed to carry voice and video communications. RJ-11: similar to RJ-45 but are smaller and have fewer connection wires. Used to connect a modem to POTS. Router: Connects two subnets. that provides network-to-network connectivity. With TCP/IP the router will forward the data to the appropriate computers on the other subnet. Connects tw or more subnets and enables computers on a subnet to send data to remote subnets; although some routers provide packet filtering capabilities, packet filtering is not a guaranteed capability with a router Remote Access Service (RAS): Security Accounts Manager (SAM): In a Win NT environment, SAM database contains user and group information for the domain. The network admin. can configure Win NT domains to trust one another so that they can share information. The Win NT NOS uses Win NTDS as part of the system of Win NT trusts and domains. Switch: a device that can be used to create virtual LANs. Simple Mail Transfer Protocol (SMTP): Uses port 25, to upload e-mail messages to e-mail servers, and e-mail servers use SMTP to transfer e-mail messages to other e-mail server. Single-mode fiber-optic cable: Constructed with an 8-micron (um) or 9-um central core with 125-um cladding. Often referred to as 8/125 cable or 9/125 cable. A 100BaseFX Ethernet network that is implemented over single-mode fiber can support a single cable segment length of 20 kilometers or greater. Implementations are more expensive than multimode fiber because single-mode fiber requires more precise connectors and use laser emitters in the transceivers. Implementations fo 100BaseFX Ethernet often require proprietary equipment and professional installation. Single points of failure: Symmetric cryptography: both users use the same shared key to encrypt and decrypt data. Digital signatures do not use symmetric cyptography. ST COnnector: Star Topology: easiest to expand or reconfigure. Easy to connect a new hub of computers to a network by making a single network connection. SM 905/906: The Sequenced Packet Exchange (SPX) protocol: Used to provide connection-oriented communications on a NetWare 3.x network. Connection-oriented protocol provides flow control, sequencing and transmission acknowledgement, which are implemented to provide increases data transmission reliability. Simple Mail Transfer Protocol (SMTP) : Uses port 25 SC Connector: a square fiber-optic connector. The male SC connector has tabs the lock into slots on the female SC connector. SVCs: Are established when communications need to be sent and are disconnected after communications are complete. Secure Sockets Layer (SSL): TCP port 443 is the well-know port assigned to SSL. SSL uses public key cryptography at the Session layer of the Open Systems Interconnection (OSI) model to secure transactions, such as financial transactions, on the Internet. The Session layer is responsible for establishing and maintaining a connection between two computers on a network, which is referred to as a session. SSL can select from Standard (DES); triple-DES; and Rivest-Shamir-Adelman (RSA) encryption technologies. Uses public key cryptography as provided by the Rivest-Shamir-Adleman (RSA) cryptography standard. SSL client contacts an SSL server, and the server sends the client its authentication information, which includes a digital certificate and a public key. The server then negotiates an encryption level, which is typically 40-bit, 56-bit, or 128-bit encryption. The client then uses the server's public key to construct a session key, which can only be decrypted by the server's secret private key. The server uses its private key to decrypt the client's session key. The server and the client use the session key to encrypt the data transferred between the cleitn and the server on the SSL connection. T1 Lines: you cannot use, hubs, analog modems, or cable modems to connect computer networks to T1 lines. Always-on digital connection to the telephone company. Most expensive solution. T3 Lines: Dedicated connection requires the installation of a special digital line; Can tranfer data at a maximum rate of 44.736 Mbps. Ticket-granting Server (TGS): Transmission Control Protocol/Internet Protocol (TCP/IP): Network communications protocol native to UNIX computers. TCP/IP is also the protocol used on the Internet. If you want the Win NT computer to connect to a UNIX network or to the Internet, then you should install TCP/IP on the Win NT computer. Each host on a TCP/IP netowrk should be assigned a unique IP address. TCP: Provides connection-oriented communications for hosts on the network. IP Provides routing and network addressing for hosts on TCP/IP networks. The UDP provides connectionless communications for hosts on TCP/IP networks. UDP and IP provide the services on a TCP/IP network that IPX provides on an IPX/SPX network. TCP/IP Loopback Address: This address enables
you to troubleshoot problems with the TCP/IP protocol stack. If
you use this address to send information, then the information will
be sent back to your computer. TCP/IP: Allows computers on one subnet to send information that is addressed to computers on the other subnet through the router. TCP port 80: A well-known TCP port for HTTP messages. TCP port 20: Assigned to FTP. TCP port 119: Assigned to the Network News Transfer Protocol (NNTP) ThickNet Ethernet: Requires special coaxial cable, which is 0.4 (1 cm)inches in diameter, has a solid copper core and is clad with yellow or orange sheathing. ThickNet Coaxial cable is often referred to as RG-8 coaxial cable, and RG-8 coaxial cable can be used for 10Base5 network backbones as long as it meets the stringent electrical specifications. Operates @ 10Mbps. AKA 10Base5. Uses a bus configuration with a linear topology. (IEEE 802.3 coaxial cable). Designed for data networks, not voice. Uses baseband signal to transmit data @ 10 Mbps over cable segments that can be amax of 500 meters in length. ThinNet Ethernet: Operates @ 10 Mbps. also known as 10Base2. Uses a bus configuration with a linear toplogy. All computers connected to amain bus cable by BNC connectors. Each end of the bus must be terminated by a 50-ohm resistor; one terminating resistor is grounded, and the other resistor is ungrounded. Asll computers on the bus have BNC T connectors connected to their NICs. Bus cable segments connect the BNC T connector on one coputer to the BNC T connector on the next computer, thus creating the network. Uses RG-58 coaxial cable to form the main bus calbe. BNC conn. are used to connect computers to the bus cable. Referred to as 10Base2/ uses a baseband signal to transmit data at 10Mbbps over cable segments; max. of 185 m in length. Token-ring Lan: usually 4 Mbps or 16 Mbps. Transport Layer of the OSI: TCP and User Datagram Protocol (UDP) both operate at the Transport layer of the Open Systems Interconnection (OSI) model. Transport layer is the fourth layer in the OSI model, is sometimes referred to as Layer 4. Protocols that operate at the Transport layer provide transport services to higher-layer protocols, such as HTTP and Trivial File Transfer Protocol (TFTP). Transport layer of OSI Model: Provides connection-oriented communications. Protocols such as TCP operate at the Transport layer. User Datagram Protocol (UDP): The UDP provides connectionless communications for hosts on TCP/IP networks. UDP and IP provide the services on a TCP/IP network that IPX provides on an IPX/SPX network. User Manager for Domains Utility: Can be used to configure user accounts to be members of groups. Also you can change passwords and permissions. Uninterupted power supplies (UPSs): provide fault tolerance for power outages. Battery power backup in event of a power failure.
Virtual Private Network (VPN): A private connection through a public network, such as the Internet. WINS: Improvement on LMHOSTS files. WINS dynamically resolves NetBIOS names to IP addresses. Used on Microsoft networks that require NetBIOS (ie. win nt 4).
100BaseFX LAN: Fiber-optic cable requires termination. End of the glass fiber in the cable must be properly sanded and polished to enable proper network communications. Improper termination can cause network connection problems. 100BaseFX Ethernet network that connects a computer to a hub can be a maximum of 2,00 meters in length. Fiber-optic communications are immune to interference by high-energy electrical sources and electrostatic discharge (ESD), which is sometime referred to as static electricity. Fiber cable is immune to these forms of interference because it uses light rather than electricity to transmit data. Normally, a communications problem is caused by a hardware malfunctiona or a software issue unrelated to the NDIS library, such as improperly configured default gateway address, would all cause a computer to be unable to connect to the Internet. Q? 50 Win 98 computers and several Win NT Server
4 computers in client/server config. NetBEUI comm. protocol. only.
Need to add a 2nd subnet to the network, and want alll computers
to communicate with any other computer on the network and to the
Internet. Answer: Install/configure a router between the two subnets, configure the computers on both subnets to use TCP/IP, and connect the router to the Internet through a proxy server. Question: Connecting Macs to a Novell NetWare
4.11 network. Example. GeoTrek Corporation
(C) Copyright 2002
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