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Difficulty: MediumIPv6 Addressing and Deployment

A network administrator is documenting the primary gateway interface for a newly provisioned IPv6 network segment. The central management portal requires all IPv6 host addresses to be recorded strictly following the RFC 5952 canonical representation standard. The interface has been assigned the uncompressed address 2001:0db8:0000:0000:00ab:0000:0000:0001/642001:0db8:0000:0000:00ab:0000:0000:0001/64. Which of the following options represents the correct RFC 5952 compressed format for this address?

  1. 2001:db8::ab:0:0:1/64Answer
  2. B
    2001:db8:0:0:ab::1/64
  3. C
    2001:db8::ab::1/64
  4. D
    2001:0db8::ab:0:0:1/64

Answer

The correct RFC 5952 representation of the IPv6 address is 2001:db8::ab:0:0:1/64.
According to RFC 5952, canonical compression requires removing leading zeros from every 16-bit hextet (reducing '0db8' to 'db8', '00ab' to 'ab', and '0001' to '1'). When an address contains two separate sequences of zero fields of equal length (in this case, two runs of two zero hextets), the double-colon (::) must compress the first sequence on the left. This yields the canonical format 2001:db8::ab:0:0:1/64.

Step-by-Step Solution

1
Suppress leading zeros in all 16-bit hex fields (hextets).
2001:0db8:0000:0000:00ab:0000:0000:0001 becomes 2001:db8:0:0:ab:0:0:1.
RFC 5952 mandates that leading zeros within each 16-bit field must be removed (e.g., 0db8 becomes db8, 00ab becomes ab, 0000 becomes 0, and 0001 becomes 1).
2
Identify candidate consecutive zero sequences for double-colon (::) compression.
Two separate zero runs of equal length exist: fields 3-4 (0:0) and fields 6-7 (0:0).
The double-colon symbol can only be used once in an IPv6 address to represent consecutive zero fields.
3
Apply RFC 5952 tie-breaking rules for equal-length zero sequences.
Compress the first zero sequence (fields 3-4), producing 2001:db8::ab:0:0:1/64.
RFC 5952 Section 4.2.3 explicitly specifies that when multiple zero sequences of equal maximum length exist, the first sequence must be compressed.

Key Concept

RFC 5952 IPv6 Address Canonical Representation and Compression Rules
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Topics

IPv6 Addressing and Deployment

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