IPv6 Hop Limit Maximum Value | Generated by AI
Question: In IPv6, what is the maximum value of the “Hop Limit” field?
Answer:
IPv6 Hop Limit Field
The correct answer is C: 255.
Explanation
The Hop Limit field in IPv6 is an 8-bit field in the IPv6 header. Here are the key details:
| Property | Value |
|---|---|
| Field Name | Hop Limit |
| Field Size | 8 bits (1 byte) |
| Maximum Value | 255 |
| Minimum Value | 0 |
Why 255?
Since the Hop Limit field is 8 bits long, it can store values from 0 to 2^8 - 1 = 255.
- Each time an IPv6 packet passes through a router (hop), the router decrements this value by 1.
- When the value reaches 0, the packet is discarded, and an ICMPv6 “Time Exceeded” message is sent back to the source.
- This mechanism prevents packets from looping indefinitely on the internet.
Comparison with IPv4
| Feature | IPv4 | IPv6 |
|---|---|---|
| Field Name | TTL (Time To Live) | Hop Limit |
| Size | 8 bits | 8 bits |
| Max Value | 255 | 255 |
| Purpose | Prevent infinite loops | Prevent infinite loops |
The IPv6 Hop Limit is functionally equivalent to the TTL field in IPv4, but renamed to better reflect its actual behavior — counting hops (router traversals) rather than time.
Why Other Options Are Wrong
- A (1024): Impossible — 8 bits cannot store values above 255.
- B (256): Impossible — 8 bits max is 255 (0–255), not 256.
- D (254): Close, but 254 is not the maximum value; 255 is still valid and achievable.