Question 1.
If an ARP packet is destined for a different subnet, the router can do what to the packet in order to route it to the proper subnet?

a) The router cannot forward the ARP packet.
b) The router replaces the source MAC address with its own.
c) The router replaces the source IP address with its own.
d) The router replaces both the source MAC address and IP address with its own.

Answer

Question 2.
What numeric notation is used to express a MAC address?

a) base 2 binary
b) base 8 octal
c) base 10 decimal
d) base 16 hexadecimal

Answer

Question 3.
What does the RARP protocol need to work correctly?
(Choose 2)

a) An RARP server
b) A TCP connection
c) A network connection
d) A UDP connection

Answer

Answers

Question 1.
If an ARP packet is destined for a different subnet, the router can do what to the packet in order to route it to the proper subnet?

a) The router cannot forward the ARP packet.
b) The router replaces the source MAC address with its own.
c) The router replaces the source IP address with its own.
d) The router replaces both the source MAC address and IP address with its own.

Answer
a) The router cannot forward the ARP packet.

Explanation
Since ARP is a broadcast packet, the router will not forward it to a different subnet since routers, by design, are used to break up broadcast domains.

However, if the router is using Proxy ARP, the router recognizes ARP requests for hosts on the "other side" of the router. The router answers those requests with an ARP reply with source IP address of the original destination host but the router's own MAC address. The router effectively "lies" to answer the ARP request, but this allows for transparent communication between the source and destination hosts.
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Question 2.
What numeric notation is used to express a MAC address?

a) base 2 binary
b) base 8 octal
c) base 10 decimal
d) base 16 hexadecimal

Answer
d) base 16 hexadecimal

Explanation
The MAC address is presented in base 16 (hexadecimal) notation. This is why you see the numbers 0-9 and the letters A-F in the MAC address.
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Question 3.
What does the RARP protocol need to work correctly?
(Choose 2)

a) An RARP server
b) A TCP connection
c) A network connection
d) A UDP connection

Answer
a) An RARP server
c) A network connection

Explanation
The RARP protocol uses a broadcast packet that is answered only by a RARP server and provides the IP address instead of a MAC address. A classic example of this is a diskless workstation where it needs the IP address each time it boots up. The workstation has a network connection to the RARP server and it already has the MAC address for the RARP server, so it sends a RARP packet, requesting the IP address. The RARP server receives the request, looks up the correct IP address, and sends back a reply with the IP address to the requesting workstation.

RARP functions at OSI Layer 3 (Network) and does not use UDP or TCP, which are OSI Layer 4 protocols.
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