How many bits are required for an IPv6 address?
2011
How many bits are required for an IPv6 address?
Answer: D. 128 — ConceptAn Internet Protocol address is a fixed-length binary identifier. For an n-bit address, there are n binary positions, and each position can be 0 or 1.…
- A.
16
- B.
32
- C.
64
- D.
128
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Show answer & explanation
Correct answer: D
Concept
An Internet Protocol address is a fixed-length binary identifier. For an n-bit address, there are n binary positions, and each position can be 0 or 1.
The protocol version specification fixes n; the address space then contains 2n possible bit patterns.
Application
IPv6 defines an address as a 128-bit identifier.
Therefore n = 128, so one IPv6 address requires 128 bits.
Cross-check and contrast
IPv6 is commonly written as eight hexadecimal groups. Each group contains four hexadecimal digits, and each digit represents 4 bits: 8 × 4 × 4 = 128 bits.
16 bits correspond to one hexadecimal group in the usual IPv6 notation.
32 bits are the complete address length used by IPv4.
64 bits are half of the full IPv6 address length and commonly occur as a prefix or interface-identifier length in a /64 subnet.
128 bits are the complete fixed length of an IPv6 address.
Hence, an IPv6 address requires 128 bits.