Chapter 6 vocabulary

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Chapter 6 vocabulary
2012-11-12 18:26:14
ccna vocab

chapter 6 vocabulary
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  1. Anti-X
    The term used by Cisco to refer to a variety of security tools that help prevent various attacks, including anti-virus, anti-phishing, and anti-spam.
  2. Connection Establishment
    The process by which a connection oriented protocol creates a connection.  With TCP, a connection is established by a three-way transmission of TCP segments.
  3. DoS
    Denial of Service.  A type of attack whose goal is to cause problems by preventing legitimate users from being able to access services, thereby preventing to normal operation of computers and networks.
  4. Error Detection
    The process of discovering whether or not a datalink level frame was changed during transmission.  This process typically uses a Frame Check Sequence (FCS) field in the datalink trailer.
  5. Error Recovery
    The process of noticing when some transmitted data ws not successfully received and resending the data until it is successfully received.
  6. Firewall
    A device that forwards packets between the less secure and more secure parts of the network, applying rules that determine which packets are allowed to pass, and which are not.
  7. Flow Control
    The process of regulating the amount of data sent by a sending computer toward a receiving computer.  Several flow control mechanisms exist, including TCP flow control, which uses windowing.
  8. Forward Acknowledgement
    A process used by protocols that do error recovery in which the number that acknowledges data lists the next data that should be sent, not the last data that was successfully received.
  9. HTTP
    Hyper Text Transfer Protocol.  The protocol used by web browsers and web servers to transfer files, such as text and graphics files.
  10. Intrusion Detection System (IDS)
    A security function that examines more complex traffic patterns against a list of both known attack signatures and general characteristics of how attacks may be carried out, rating each perceived threat and reacting to report more significant threats.
  11. Intrusion Prevention System
    A security function that examines more complex traffic patterns against a list of both known attack signatures and general characteristics of how attacks may be carried out, rating each perceived threat and reacting to prevent more significant threats.
  12. Ordered Data Transfer
    A networking function included in TCP, in which the protocol defines how the sending host should number the data transmitted, defines how the receiving device should attempt to reorder that data if it arrives out of order, and specifies to discard the data if it cannot be delivered in order.
  13. Positive Acknowldegment and Retransmission (PAR)
    A generic reference to how the error recovery feature works in many protocols, including TCP, in which the receiver must send an acknowledgement that either implies that data was (positivley) received, or send an acknowledgment that implies some data was lost, so the sender can resend the lost data.
  14. Segment
    In TCP a term used to describe a TCP header and its encapsulated data (also called an L4PDU).  Also in TCP, the process of accepting a large chunk of data from the application layer and breaking it into smaller peices that fit into TCP segments.  In Ethernet, a segment is either a single ethernet cable or a single collision domain ( no matter how many cables are used.)
  15. Sliding Windows
    For protocols such as TCP that allow the receiving device to dictate the amount of data the sender can send before receiving an acknowledgement - a concept called a window - a reference to the fact that the mechanism to grant future windows is typically just a number that grows upwards slowly after each acknowledgment, sliding upward.
  16. URL
    Universal Resource Locator.  A standard for how to refer to any piece of information retreivable via a TCP/IP network, most notably used to identify web pages.  For example, is a URL that identifies the protocol (HTTP), hostname (, and web page (/univercd).
  17. Virtual Private Network
    The process of securing communication between two devices whose packets pass over some public and unsecured network, typically the internet.  VPNs encrypt packets so that communication is private and authenticate the identity of the end points.
  18. VoiP
    Voice over IP.  The transport of voice traffic inside IP packets over an IP network.
  19. Web Server
    Software running on some computer that stores web pages and sneds those web pages to web clients (web browsers) that request web pages.