Wednesday, July 11, 2007

Here are the answers to Tuesday's Cisco certification exam practice questions!

CCNA Exam:

What summary route can be used to advertise the following four routes? /16 /16 /16 /16

Answer:, or /14 in prefix notation.

To manually summarize routes, break them down into binary. Then, working from left to right, note where the routes no longer have a bit in common. The value to the left of that point is your summary, and the number of bits in common is your subnet mask. 00001010 00000100 00000000 00000000 00001010 00000101 00000000 00000000 00001010 00000110 00000000 00000000 00001010 00000111 00000000 00000000

Working from left to right, these are the common bits:
00001010 000001

That gives us, and the subnet mask will have the first 14 bits set to 1. That results in a decimal value of

CCNP Certification / BSCI Exam:

You are examining an IPv6 address and notice two consecutive colons. What does this represent, if anything?

Answer: Those two colons represent a string of zeros. This is referred to as zero compression, but can only be done once in a single IPv6 address. Leading zero compression, though, can be done as many times as is appropriate in an IPv6 address.

Original format: 1234:1234:0000:0000:0000:0000:3456:3434

Using zero compression: 1234:1234::3456:3434

CCNP Certification / BCMSN Exam:

How many bytes are added to a frame as a result of ISL encapsulation?

The header is 26 bytes, the trailer containing the CRC value is 4 bytes, for a total of 30 bytes.

CCNP Certification / ISCW Exam:

What command disables ICMP redirects?

Answer: no ip redirects.

CCNP Certification / ONT Exam:

What number and name are given to the highest possible CoS value?

Answer: The highest possible CoS value is 7 (111 in binary), known commonly as Network.

New questions posted later today!

To your success,

Chris Bryant
CCIE #12933

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