Ch. 3 Key Terms

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Ch. 3 Key Terms
2011-12-12 17:47:11
Chapter Three Application Layer Functionality Protocols Network Fundamentals CCNA Exploration Companion Guide

Chapter Three Application Layer Functionality and Protocols Network Fundamentals, CCNA Exploration Companion Guide
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  1. data
    Application layer protocol data unit.
  2. source device
    The device that is originating the PDU.
  3. DNS
    Domain Name System

    Internet-wide system by which hierarchical set of DNS servers collectively hold all the name-IP address mappings, with DNS servers referring users tot he correct DNS server to successfully resolve a DNS name.
  4. RFC
    Requests for Comments

    Series of documents and memoranda encompassing new research, innovations, and methodologies applicable to Internet technologies.

    Reference for how technologies should work.
  5. syntax
    The structure and order of words in a computer language.
  6. session
    A related set of communications transactions between two or more network devices.
  7. client
    Network device that accesses a service on another coputer remotely by accessing the network.
  8. server
    Can refer to computer hardware that is to be used by multiple concurrent users.

    Can refer to computer software that provides services to many users.

    Example: consists of web server software running on some computer.
  9. daemon
    Computer program that runs in the background and is usually initiated as a process.

    Ofter support server processes.
  10. peer
    A host or node that participates in some form of a group.

    Peers that participate jointly in the same activity, each having a server and client component.
  11. scheme
    A plan, design, or program of action to be followed.

    Sometimes an addressing plan is called an addressing scheme.
  12. IP Address
    32-bit number written in dotted decimal notation, used by the IP to uniquely identify an interface connected to an IP network.

    Also used as a destination address in an IP header to allow routing.

    Or as a source address to allow a computer to receive a packet and to know which IP address to send a response to.
  13. domain name
    Name defined by DNS that uniquely identifies a computer in the Internet.

    Corresponds with the IP address

    ex: ip address
  14. network address
    A dotted decimal number defined by the IPv4 protocol to represent a network or subnet.

    REpresents the network that hosts reside in.

    AKA a network number or network ID
  15. resource record
    DNS data records.

    Precise format is defined in RFC 1035.

    Important fields: name, class, type, and data.
  16. DNS resolver
    Client end of the DNS client-server mechanism.

    Creates queries sent across a network to name a server, interprets responses, and returns information to the requesting programs.
  17. nslookup
    A part of a computer network that every device communicates with using the same physical medium.

    Can be extended by hubs or repeaters.
  18. query
    A request for information.

    Queries are answered with replies.
  19. cache
    Temporary storage where data that has been retrieved or calculated and is accessed frequently can be stored.

    Reduces the average access time and reduces the overhead of recalculating the data.
  20. authoritative
    A source of information that is highly reliable and known for its accuracy.
  21. plug-in
    In a web browser, an application the browser uses, inside the browser window, to display some types of content.

    Ex: typically uses a plug-in to display video.
  22. HTTP
    Hypertext Transfer Protocol

    Defines the commands, headers, and processes by which web servers and web browsers transfer files.
  23. distributed
    Method of computer processing in which different parts of a program run simultaneously on two or more computers that are communicating with each other over a network.
  24. collaborative
    Information systems that allow the creation of a document(s) that can be edited by more than one person in real time.
  25. encryption
    Process of obscuring information to make it unreadable.

    Applies mathematical formula to the data along with a secret number (encryption key) resulting in an encrypted data packet and is sent through the network.
  26. POP
    Post Office Protocol

    A protocol that allows a computer to retrieve e-mail from a server.
  27. SMTP
    Simple Mail Transfer Protocol

    Application protocol typically not used by an end user.

    Used by the network management software and networking devices to allow a network engineer to monitor and trouble shoot network problems.
  28. MUA
    Mail User Agent Program

    Used to download and send e-mail.

    • Use POP3 to receive e-mails
    • Use SMTP to send e-mails
  29. spam
    Unsolicited commercial e-mail.
  30. gateway
    Relatively general term referring to different kinds of networking devices.

    {Routers were once galled gateways}
  31. DHCP
    Dynamic Host Configuration Protocol

    Used to dynamically assign IP config's to hosts.

    Services defined by the protocol are used to request & assign IP addresses, default gateway, and DNS server address to a network host.
  32. subnet mask
    A dotted decimal number that helps identify the structure of IP addresses.

    Mask represents the network and subnet parts of related IP addresses with binary 1s and the host part of related IP addresses with 0s.
  33. broadcast
    A form of transmission where one device transmits to all devices within the network or on another network.
  34. SMB
    Server Message Block

    An application level network protocol mainly applied to shared access to files, printers, serial ports, and miscellaneous communications between nodes on a network.
  35. UNIX
    A multiuser, multitasking operating system (196/70s)

    AT&T employees developed
  36. IAC
    Interpret as Command

    In Telnet application, commands are always introduced by a character with the decimal code 255, known as an IAC character