712 Appendix A: Answers to the "Do I Know This Already?" Quizzes and Q&A Sections
12
Describe the features required for a protocol to be considered connection-oriented.
The protocol must either exchange messages with another device before data is allowed
to be sent, or some pre-established correlation between the two endpoints must be defined.
TCP is an example of a connection-oriented protocol that exchanges messages before data
may be sent; Frame Relay is a connection-oriented protocol for which pre-established
correlation between endpoints is defined.
13
In a particular error-recovering protocol, the sender sends three frames, labeled 2, 3, and
4. On its next sent frame, the receiver of these frames sets an acknowledgment field to 4.
What does this typically imply?
Frames up through number 3 were received successfully. Most windowing, error-recovery
protocols use forward acknowledgment.
14
Name three connection-oriented protocols.
TCP, SPX, LLC Type 2, and X.25 are some examples of connection-oriented protocols
that provide error recovery. ATM and Frame Relay are also connection-oriented, but
without error recovery.
15
What does MAC stand for?
MAC stands for Media Access Control.
16
Name three terms popularly used as a synonym for MAC address.
NIC address, card address, LAN address, hardware address, Ethernet address, Token Ring
address, FDDI address, and burned-in address are all synonymous with MAC address. All
of these names are used casually and in formal documents, and refer to the same 6-byte
MAC address concept as defined by IEEE.
17
Are IP addresses defined by a Layer 2 or Layer 3 protocol?
IP addresses are defined by the IP part of TCP/IP, which is the second layer of TCP/IP.
However, compared to OSI, IP most closely matches OSI Layer 3 in function, so the
popular (and CCNA exam) answer is Layer 3.
18
Are IPX addresses defined by a Layer 2 or Layer 3 protocol?
IP addresses are defined by a Layer 3 protocol.
19
Are OSI NSAP addresses defined by a Layer 2 or Layer 3 protocol?
OSI NSAP addresses are defined by a Layer 3 protocol. Of course, they are truly Layer 3
because they are defined by OSI. The number of bits in the address is variable. However,
it is highly unlikely that questions about NSAPs would be on the exam because they are
not mentioned in any objective and are not covered in any class.
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