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2011-08-17 23:52:22
Cisco ICND1

Cisco ICND1 test
Show Answers:

  1. What are the 7 layers of the OSI model?
    • Physical
    • Data Link
    • Network
    • Transport
    • Session
    • Presentation
    • Application
  2. What is same-layer interaction on different computers?
    The two computers use a protocol to communicate with the same layer on another computer. The protocol defined by each layer uses a header that is transmitted between the computers, to communicate what each computer wants to do.
  3. What is adjacent-layer interaction on the same computer?
    On a single computer, one layer provides a service to a higher layer. The software/hardware that implements the higher layer requests that the next lower layer perform the needed function.
  4. What is a segment, packet and frame
    • Segement: TCP header and data
    • Packet: IP header and data (may include TCP header in data)
    • Frame: Link Header - data - Link Trailer (data may include packet and segment headers)
  5. OSI model vs. TCP/IP model
    OSI: physical, data link, network, transport, session, presentation, application

    TCP/IP: application, transport, internet, network access
  6. What are the benefits of a layered network model?
    Less complex, standard interfaces (routers/switches), easier to learn, easier to develop (program changes and product development), multivendor interoperability, modular engineering (web browser or Microsoft TCP/IP)
  7. Define decapsulation
    on a computer that receives data over a network, the process in which the device interprets the lower-layer headers and, when finished with each header, removes the header, revealing the next-higher-layer PDU (protocol data unit; grouping of info by OSI layer)
  8. Define encapsulation
    the placement of stat from a higher-layer protocol behind the header (sometimes header and trailer_ of the next-lower-layer protocol. IE. an IP packet being encapsulated in and ethernet header and trailer to be sent over ethernet.
  9. Define frame
    refers to data link header and trailer, plus the data encapsulated between the header and trailer
  10. Define networking model
    term referring to any set of protocols and standards collected into a comprehensive grouping that, when followed by the devices in a network, allow all devices to communicate. IE. TCP/IP or OSI models.
  11. Define packet
    logical grouping of informantion that includes the network layer header and encapsulated data, but does not include any headers or trailer below the network layer.
  12. Define PDU
    Protocol Data Unit: OSI term to refer to generically grouping of information by a layer of the OSI model.
  13. Define Segment
    In TCP, used to describe a RCP header and its encapsulated data (L4PDU). Also in TCP, the process of accepting a large chunk of data from the application yaer and breaking it into smaller pieces that fit into TCP segments. Segment in Ethernet is either single cable or a collision domain.
  14. What are the functions of the OSI layers?
    • Physical: defines cabling and connectors, procedure details for transmitting bits
    • Data Link: formats data into frames appropriate for transmission on layer 1. Defines rules for when layer 1 medium can be used and means by which to recognize transmission errors
    • Network: logical addressing, routing and path determenation
    • Transport: provides services between host computers. Connection establishment and termination, flow control, error recovery, segmentation of data for transmission
    • Session: establishes and maintains end to end bidirectional flows between end points
    • Presentation: defines the format and organization of data, includes encryption
    • Application: interfaces between network and application software, includes authentication services
  15. What is ethernets speed, name, IEEE standard and cable type/length?
    10 mbps, 10base-t, IEEE 802.3, copper 100m
  16. What is fast ethernets speed, name, IEEE standard and cable type/length?
    100 mbps, 100base-t, IEEE 802.3u, copper 100m
  17. What is Fiber Gigabit ethernet's speed, name, IEEE standard and cable type length?
    1000 mbps, 1000base-lx or 1000base-sx, IEEE 802.3z, fiber 550sx/5km lx
  18. What is Copper ethernet's speed, name, IEEE standard and cable type/length?
    1000 mbps, 1000base-t, 802.3ab, 100m
  19. What does CSMA/CD stand for?
    Collision sense multiple access with collision detection
  20. Summarize CSMA/CD
    • -device that wants to send a frame waits until the LAN is silent before attempting to send.
    • -If a collision does occur, the device that cause the collision waiats a random amount of time and then trys again.
  21. How does a crossover cable work?
    Send and recieve pins are swapped on one end, pins 1 & 2 are 3 & 6, pins 3 & 6 are 1 & 2.
  22. Devices that transmit on 1 &2 and receive on 3 & 6?
    PC NIC's, routers, WAP ethernet interface, printer ethernet interfaces
  23. Devices that transmit on 3 & 6 and receive on 1 & 2?
    Hubs and switches
  24. Explain the Steps of CSMA/CD
    • 1. device with a frame to send listens until the ethernet is not busy
    • 2. when ethernet is not busy, the sender begins sending the frame
    • 3. the sender listens to make sure that no collision occurred.
    • 4. if collision occurs, the devices that were sending frames each send a jamming signal to ensure all stations recognize collision.
    • 5. after jamming is complete, each sender randomizes a timer and waits that long before resending the collided frame
    • 6. when timer expires the process starts over
  25. Define full-duplex
    any communication in which the communicating devices can send and recieve data.
  26. Define half-duplex
    any communication in which only one device at a time can send data
  27. Define hub
    LAN device that allows for centralized cabling, repeats any received data out all ports (logical bus). Layer 1 device
  28. Define pinout
    Documentation and implementation of which wires inside cable connect to each pin position in a connector
  29. Define protocol type
    Field in a LAN header that identifies the type of header that follows the LAN header. Includes DIX (ethernet field, IEEE 802.2 DSAP field and SNAP protocol field
  30. Define shared ethernet
    Ethernet that uses a hub or coaxial cable, results in devices taking turns sending data and sharing bandwidth.
  31. Define switch
    Network device that filters, forwards, and floods ethernet frames based on destination address of each frame.
  32. Define switched ethernet
    Ethernet that uses a switch, not a hub. Each device connected to one port and do not have to contend for bandwidth on another port