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Difficulty: EasyIPv6 Addressing Concepts and Header Structure

A network administrator is standardizing network documentation and needs to compress the full 128-bit IPv6 address `2001:0db8:0000:0000:0000:0000:0000:0001` into its valid shorthand form. Which of the following represents the correct compressed IPv6 address?

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

Answer

The correct compressed shorthand representation is 2001:db8::1.
The shorthand representation `2001:db8::1` correctly suppresses the leading zero in the second block (0db8 to db8) and compresses the five consecutive blocks of zeros into a single double colon (`::`).

Step-by-Step Solution

1
Omit leading zeros in each 16-bit hexadecimal block.
2001:0db8 becomes 2001:db8.
Leading zeros in hexadecimal hextets are redundant and can be omitted.
2
Compress contiguous fields of zeros using double colon (::) notation.
The five contiguous blocks of 0000 (:0000:0000:0000:0000:0000:) become ::.
Standard RFC 5952 zero compression permits replacing consecutive zero blocks with double colons.
3
Verify that the double colon is only used once in the entire address.
2001:db8::1 is formed cleanly with exactly one double colon.
Using double colons more than once renders an IPv6 address ambiguous when expanding back to 128 bits.

Key Concept

IPv6 Address Compression Rules (RFC 5952)
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Topics

IPv6 Addressing Concepts and Header Structure

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