GCIH · Question #609
If a router received an IPv6 packet with a Hop Limit of 1, which of the following ICMP messages would it send back to the originating host?
The correct answer is D. Time Exceeded. The IPv6 Hop Limit field is similar to the IPv4 TTL field. When a router receives a packet, it decrements the Hop Limit (or TTL value for IPv4) by one. It then inspects that value. It if is 0, the router will send an ICMP Time Exceeded message back to the originating host. The IC
Question
If a router received an IPv6 packet with a Hop Limit of 1, which of the following ICMP messages would it send back to the originating host?
Options
- AInformation Request
- BRedirect
- CHost Unreachable
- DTime Exceeded
- ETimestamp
How the community answered
(29 responses)- A3% (1)
- C3% (1)
- D93% (27)
Explanation
The IPv6 Hop Limit field is similar to the IPv4 TTL field. When a router receives a packet, it decrements the Hop Limit (or TTL value for IPv4) by one. It then inspects that value. It if is 0, the router will send an ICMP Time Exceeded message back to the originating host. The ICMP Timestamp request allows the originating host to query another host for the current time. The ICMP Destination Unreachable (Type) Host Unreachable (Code) message indicates the router was unable to contact the destination host. A router would send an ICMP Redirect to the originating host if the router determined a more optimal route to the destination host existed. The ICMP Information Request is sent by a host to determine the number of the network which it is on (and the destination address in the packet is all zeros).
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