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Difficulty: EasyIPv6 Addressing Concepts and Header Structure

An entry-level technician is reviewing core IPv6 specifications, address shorthand rules, and packet structures. Which of the following statements correctly describe valid IPv6 characteristics? (Select TWO.)

  1. Leading zeros within any 16-bit hexadecimal block may be omitted.Answer
  2. The primary IPv6 header has a fixed size of 40 bytes.Answer
  3. C
    The double colon (::) notation can be used twice in an address if separated by non-zero blocks.
  4. D
    Trailing zeros within a 16-bit hexadecimal block may be suppressed to shorten the address.

Answer

Leading zeros within any 16-bit hexadecimal block may be omitted, and the primary IPv6 header has a fixed size of 40 bytes.
Leading zeros within a 16-bit block can be safely omitted without changing the block's numeric value. Furthermore, the standard primary IPv6 header is simplified with a fixed size of 40 bytes to optimize routing lookup performance.

Step-by-Step Solution

1
Analyze zero suppression rules for 16-bit IPv6 hexadecimal fields.
Leading zeros inside a field (such as 0042) can be shortened to 42. Trailing zeros must remain intact to preserve the position and value of the digits.
Only leading zero suppression preserves the original numerical value of a nibble field.
2
Analyze the rule regarding double colon (::) compression.
A double colon represents consecutive all-zero blocks, but it can only appear once in an address.
If multiple double colons were permitted, a host would be unable to calculate the exact number of zero blocks belonging to each sequence.
3
Evaluate the structural specification of the main IPv6 header.
The standard base IPv6 header is fixed at 40 bytes in length.
A predictable fixed header length speeds up hardware switching and routing compared to IPv4's variable header length.

Key Concept

IPv6 Address Representation Rules and Primary Header Architecture
Estimated Time:1m 0s
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Topics

IPv6 Addressing Concepts and Header Structure

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