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Difficulty: EasyIPv6 Addressing and Deployment

A network administrator is documenting a newly assigned IPv6 address with the uncompressed form 2001:0db8:0000:0000:0005:0000:0000:0001. Which of the following options represents the correctly compressed IPv6 address according to standard RFC 5952 formatting rules?

  1. 2001:db8::5:0:0:1Answer
  2. B
    2001:db8::5::1
  3. C
    2001:db8:0:0:5::1
  4. D
    2001:0db8:0:0:5:0:0:1

Answer

2001:db8::5:0:0:1
The address 2001:db8::5:0:0:1 is correct because standard RFC 5952 rules require suppressing leading zeros in all 16-bit fields (changing 0db8 to db8, 0005 to 5, and 0001 to 1). Furthermore, when two sequences of zero blocks are of equal length (here, two 0000 blocks each), the first sequence must be replaced by a double colon (::), leaving the second sequence written as explicit zeros.

Step-by-Step Solution

1
Suppress leading zeros in each 16-bit block.
2001:0db8 becomes 2001:db8, 0005 becomes 5, and 0001 becomes 1, resulting in 2001:db8:0:0:5:0:0:1.
RFC 5952 mandates that leading zeros within any 16-bit field must be suppressed.
2
Identify consecutive blocks of zeros.
There are two separate zero sequences: blocks 3-4 (0:0) and blocks 6-7 (0:0). Both have a length of two blocks.
Double-colon compression (::) can only be applied to consecutive 16-bit fields of zeros.
3
Apply double-colon compression to the first longest sequence of zero blocks.
Compress blocks 3-4 to obtain 2001:db8::5:0:0:1.
When multiple zero sequences of equal length exist, RFC 5952 specifies that the first sequence must be compressed, and :: must never be used more than once in an address.

Key Concept

RFC 5952 IPv6 Address Compression Rules
Estimated Time:45s
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Topics

IPv6 Addressing and Deployment

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