Which Internet control message protocol (ICMPv6) message type would you receive if the Hop
limit field reached zero?

A.
Time exceeded.

B.
Destination unreachable.

C.
Parameter problem.

D.
Redirect.

Explanation:
If a router receives a packet with a Hop Limit of zero, or a router decrements a packet’s Hop Limit
to zero, it MUST discard the packet and send an ICMPv6 Time Exceeded message with Code 0 to
the source of the packet. This indicates either a routing loop or too small an initial Hop Limit value.
(Reference: RFC 2463)
Incorrect Answers:
C: If an IPv6 node processing a packet finds a problem with a field in the IPv6 header or extension
headers such that it cannot complete processing the packet, it MUST discard the packet and
SHOULD send an ICMPv6 Parameter Problem message to the packet’s source, indicating the
type and location of the problem. (Reference: RFC 2463)
D: Neighbor Discovery defines five different ICMP packet types: A pair of Router Solicitation and
Router Advertisement messages, a pair of Neighbor Solicitation and Neighbor Advertisements
messages, and a Redirect Message. The Redirect is used by routers to inform hosts of a better
first hop for a destination. )Reference: RFC 2461)