| A | B |
|---|
| Network | Two or more connected computers that share data |
| Communication | Occurs through protocols |
| WAN | Network over large geographical area |
| LAN | Network over limited geographical area |
| Public Switched Telephone Network (PSTN) | one of the oldest existing networks |
| IP Telephony | voice transmissions delivered in digital form |
| Mainframe (centralized) computing | Provided the first practical network solution |
| Mainframe liabilities | Handles all the processing work |
| The future of mainframes | Still prevalent in universities and some businesses |
| Two Tiered | 1stformatting info on screen; 2ndprocess logic and storage |
| Three Tiered | 1stclient; 2ndshared server; 3rdserver and database; |
| Scalable | Can adjust to demands easily |
| NOC | A specific location from which a network is managed; monitored and maintained |
| Protocols | Communication rules |
| Transmission Media | Components necessary to connect computers |
| Network Services | Shared resources |
| p2p | uses software to participate in decentralized networks on the Internet |
| Physical Network Topologies | The basic design of a network. Includes the physical components and layout. |
| Bus Networks | All components use the same cable |
| Star Network | Network nodes are connected through a central device |
| Ring Network | No central connection point |
| Hybrid Network | Combines bus; star and ring topologies |
| Mesh Network | Devices are connected with multiple paths |
| NOS | Manages resources on a network |
| OSI/RM | Defined by the International Organization for Standardization in 1983 |
| Application Layer Position | Layer 7 |
| Application Layer Purpose | File transfer |
| Presentation Layer Position | Layer 6 |
| Presentation Layer Purpose | Provides transformations on data so that it is presentable |
| Session Layer Position | Layer 5 |
| Session Layer Purpose | Establishes; manages; and terminates sessions (connections) between applications |
| Transport Layer Position | Layer 4 |
| Transport Layer Purpose | Provides reliable transport of data between end points |
| Network Layer Position | Layer 3 |
| Network Layer Purpose | Organizes data into datagrams (packets) |
| Data Link Layer Position | Layer 2 |
| Data Link Layer Purpose | Provides reliable transit of data across a physical link |
| Physical Layer Position | Layer 1 |
| Physical Layer Purpose | Transmits and receives bits |
| Headers (OSI/RM layer information) | Information that is added and subtracted as the packet moves through the layers |
| Trailer (information that validates the packet) | Cyclical Redundancy Check (CRC) |
| Application layer | SMTP; POP3; IMAP; HTTP |
| Transport layer | TCP; SPX |
| Network layer | IP; IPX |
| Data link layer | Ethernet; Token Ring |
| Connection-Oriented (stateful) | Requires a connection at both ends before sending a packet across the network |
| Connectionless (stateless) | Packet is sent without establishing a connection first |
| Routable | TCP/IP and IPX/SPX |
| Nonroutable | NetBEUI; NetBIOS; SNA; LAT; DLC |
| Transmission Control Protocol/Internet Protocol (TCP/IP) | Default protocol for the Internet |
| TCP | Connection-oriented (stateful) |
| IP | Connectionless (stateless) |
| User Datagram Protocol (UDP) | Connectionless (stateless) |
| Combining protocols | Connectionless and connections-oriented |
| Binding | attach the protocol to the NIC |
| Binding order | For use when using multiple protocols |
| LAN (local area network) | A group of computers connected within a confined geographic area |
| WAN (wide area network) | A group of computers connected over |
| NAPs | Junction between high speed networks |
| Segments | Any piece or part of a larger structure |
| Network Interface Card (NIC) | Interface between the computer and the network |
| Repeaters | Low level device that amplifies the signal allowing it to travel farther |
| Hub | Central component in a star network |
| Bridge | Device that filters frames based on physical addresses (MAC) |
| Routers | Forwards messages based on logical addresses(IP) |
| Switches | Direct the flow of information from one node to another |
| Gateways (protocol converters) | Connects networks running different protocols |
| Channel Service/Data Service Unit (CSU/DSU) | Terminates physical connections |
| Modems | Device that translates analog (phone) signals into digital (computer) signals |
| Patch Panels | Centralized connection point between cables from other locations can be connected to each other |
| Firewall | Secure computer placed between a trusted and untrusted network |
| Twisted-pair Cable (10BaseT; Ethernet) | Most commonly used in networks |
| Coaxial Cable (thicknet; thinnet) | High-capacity cable for video and communication networks |
| Fiber-optic Cable (single & multi mode) | Uses light signals |
| Wireless | Carries data signals through spectrum technologies |
| Direct Sequence Spread Spectrum(DSSS) | Current wireless method |
| Frequency Hopping Spread Spectrum (FHSS) | Narrowband network |
| Twisted Pair | Prone to electromagnetic interference |
| Coaxial Cable | Not easily bendable |
| Thicknet | 500 meters |
| Thinnet | 185 meters |
| Fiber-optic Cable | No electromagnetic interference issues |
| Single mode | 3000 meters |
| Multimode | 1000 meters |
| Wireless | 11 54 Mbps |
| WAP | Central access point |
| Wired Equivalency Privacy (WEP) | Encryption in 64 256bit keys |
| MAC address filtering | Allows only certain MAC addresses to access the network |
| Synchronous Transmission | Devices share a transmission clock and rate |
| Asynchronous Transmission | No clock; not synchronized with another device |
| Simplex | data travels in one direction only |
| Half duplex (modems; walkie-talkies; Ethernet) | Travels in 2 directions; one direction at a time |
| Full Duplex (Fast Ethernet) | Travels in 2 directions at the same time |
| Baseband Transmission | Uses the entire bandwidth for a single channel (digital) |
| Broadband Transmission | Divides the media into multiple channels (analog) |
| IEEE 802.2 | Divides the OSI Data Link layer into two sublayers: LLC and MAC |
| IEEE 802.12 100VG-AnyLAN | Supports access method called demand priority |
| X.25 | Original packet-switching from ARPANET |
| Fast packet switching | Used on the Internet |
| ATM | Use both LAN and WAN |
| North American digital transmission format | Provides dedicated and private-line services for digital voice and data transmission |
| T1 | 1.544 Mbps |
| T2 | 6.312 Mbps |
| T3 | 44.736 Mbps |
| T4 | 274.176 Mbps |
| European digital transmission format | Provides dedicated and private-line services for digital voice and data transmission |
| E1 | 2.048 Mbps |
| E2 | 8.448 Mbps |
| E3 | 34.368 Mbps |
| E4 | 139.264 Mbps |
| E5 | 565.148 Mbps |
| TCP/IP Application to OSI Application & Presentation | This is the layer closest to the user |
| TCP/IP Transport to OSI Transport and Session | Accepts application layer data |
| TCP/IP Internet to OSI Network | Addresses and routes packets |
| TCP/IP Network Access to OSI Physical and Data Link | Accepts datagrams from the Internet Layer |
| RFCs | Published documents of interest to the Internet community |
| States | Process before protocol becomes a standard |
| Experimental | Not intended for operation except in experiment |
| Proposed | Testing and research stage |
| Draft | Test results are analyzed; feedback is requested |
| Historic | Protocols replaced by more recent ones |
| Informational | Protocols developed outside of the IETF (usually by vendors) |
| Network Access Layer | Ethernet; LAN; WAN |
| Internet Layer | IP; ICMP; IGMP; ARP; RARP |
| Transport Layer | TCP; UDP |
| Application Layer | HTTP; FTP; TFTP; TELNET; NNTP; SMTP; SNMP; DNS; BOOTP; DHCP |
| Demultiplexing Routing | Process of choosing a path to send packets |
| Direct Routing | Sends information to hosts within the same physical network |
| Indirect Routing | Packets move between outside networks; requiring a router |
| Routing Process | Packet must have a destination address |
| Table of addresses | Input by hand (static routing) |
| Interior Protocols | Used within a company network |
| RIP | protocol that maintains the best closest route to a destination |
| OSPF | protocol that uses bandwidth; connections and security to determine the best route to a destination |
| Exterior Protocols | Used outside a company network |
| Port Numbers | Contained in packet information |
| Address Form | Contains the network portion (N) and host portion (h) |
| Class A | N.h.h.h |
| Class B | N.N.h.h |
| Class C | N.N.N.h |
| Class A | Numbered from 0 - 126 |
| Class B | Numbered from 128 - 191 |
| Class C | Numbered from 192 - 223 |
| Class D | Numbered from 224 239 |
| Class E | Numbered from 240 247 |
| Loopback 127 | Used for troubleshooting and diagnostics |
| Broadcast - 255 | Used to broadcast packets to ALL hosts on the network |
| Reserved | 10; 172; and 192 (in the first octet); Used for private networks |
| Shortcomings of IPv4 | Limited address space |
| Strengths of IPv6 | More efficient and requires less administrative overhead than IPv4 |
| Default gateway | The device that routes information out of the LAN |
| Broadcast address | Sends messages to all the network hosts |
| Network Addresses | Contain a 0 in the host portion of the address |
| Host Addresses | Can not contain a 0 in the host portion of the address |
| Ping | Determines connectivity between source and destination |
| Tracert or Traceroute | Determines the path between source and destination |
| Netstat | Displays the contents of network data structures |
| Ipconfig (WinNT; 2K or XP) winipcfg (Win 95; 98; Me) | Displays the physical address; the IP address; subnet mask and default gateway |
| Network Analyzers | Captures data as it moves through the network |
| File servers | network servers that store data files and programs that can be shared by network users |
| Print servers | network servers that allow multiple users to send print jobs to the same physical printer |
| Line Printer/Line Printer Daemon (LPR/LPD) | printing protocol in UNIX that allows users to submit print jobs to network printers |
| HyperText Transfer Protocol (HTTP) Servers | Servers act as delivery systems |
| MIME (Multipurpose Internet Mail Extensions) | Protocol that identifies files types and encodes and decodes the file |
| Security and OS Security | Uses permissions to restrict access |
| Access Control | Defines access to the files residing on the server |
| Virtual Directories (aliases) | Allows mapping of URLs to file names |
| Logging | Log requests and information |
| Access data | Logs all HTTP commands |
| Referrer data | Logs how many times the site is accessed |
| Error data | Server errors; dropped TCP connections and access violations |
| Database | a file that stores information in a series of tables and columns |
| Relational database | a database consisting of two or more tables related by a common field |
| Database server | a server that presents relational databases and makes it possible for remote individuals to access the data |
| Proxy server | an intermediary between a network host and other hosts outside the network |
| Mailing List Manager (MLM) | the interface that allows you to configure a mailing list server |
| Buffer | cache of memory that stores frequently-used data to allow for faster access times |
| DNS | Mechanism used on the Internet to translate host computer names into IP addresses |
| Hosts File | File referenced locally by applications and commands for name-to-address resolution |
| DSN Server Types | Root; primary; secondary; caching-only; forwarding |
| DNS Records | Entries in DNS database that provide additional routing and resolution information |
| Domain Name Server (DNS) | Distributed database |
| nslookup | Used to query Internet domain name servers to learn name-to-IP-address mappings |
| File Transfer Protocol (FTP) Servers | Used for uploading and downloading files |
| Certificate Server | Validate or certify keys (calculated text strings used for security) |
| News Servers | Uses Network News Transfer Protocol (NNTP) |
| Directory Server | Identifies all resources on a network; then makes them available to authenticated users |
| LDAP | TCP/IP protocol that allows communication on both intranets and the Internet |
| Catalog servers | Index databases; files and information and allow keyword; Boolean and other searches |
| Fax servers | Provide a centrally located fax system |
| Transaction servers | Guarantee that all required databases are updated when a transaction takes place |
| Daemon | UNIX program initiated at startup; runs in the background until required |
| inetd | Daemon that listens on specified TCP and UDP ports (0 to 1023) and launches services to support requests it receives |
| xinetd | Modified form of inetd that is more secure; provides more control over how daemons are run and which remote systems can use a particular daemon |
| Mirrored Server | Provides data redundancy by writing to two physical hard drives each time a write operation occurs |
| Apache Web server | Used by more than half of all Web sites |
| Microsoft IIS | Includes HTTP; FTP; NNTP; SMTP; certificate; ASP; index (catalog) and transaction services |
| Lotus Domino series | Includes all the most-used servers; including certificate; HTTP; SMTP and FTP |
| Sun ONE servers | Support many platforms; including OS/2; Windows NT and 2000; Solaris; AIX; HP-UX; AS/400 and S/390 |
| Java servlet | Java code that is compiled and runs solely on Web servers |
