A network administrator is reviewing IPv6 deployment standards and packet headers for an enterprise network redesign. Which of the following statements accurately describe valid IPv6 address representation rules or IPv6 header characteristics? (Select TWO.)
- The double-colon shorthand (::) can be applied only once within an IPv6 address to compress consecutive zero fields.Answer
- The Hop Limit field in the IPv6 base header serves the same loop-prevention purpose as the Time to Live (TTL) field in IPv4.Answer
- CAn IPv6 address can contain two double colons (::) provided that each represents a sequence of at least four hex nibbles.
- DThe standard IPv6 base header utilizes a variable length structure that includes optional fields directly within the 40-byte base header.
Answer
The double-colon shorthand (::) can be applied only once within an IPv6 address to compress consecutive zero fields, and the Hop Limit field in the IPv6 base header serves the same loop-prevention purpose as the Time to Live (TTL) field in IPv4.
The statement specifying that the double-colon shorthand (::) can be used only once is correct because multiple instances prevent deterministic expansion of the 128-bit address. The statement noting that the Hop Limit field replaces the IPv4 Time to Live (TTL) field is also correct, as both fields serve to drop packets that exceed maximum hop counts to prevent routing loops.
Step-by-Step Solution
Key Concept
IPv6 Address Compression Rules and Base Header Architecture