Function of the Hop Limit Field in IPv6 Header

C

The correct answer is C. It replaces the time-to-live (TTL) field in IPv4.

In IPv6, the hop limit field replaces the time-to-live (TTL) field in IPv4. The hop limit field serves the same purpose as the TTL field, which is to prevent packets from circulating indefinitely in a network.

When an IPv6 packet is sent, the hop limit field is set to a value by the sender. Each time the packet is forwarded by a router, the hop limit field is decremented by 1. When the hop limit field reaches 0, the packet is discarded and an error message is sent back to the sender.

Unlike the TTL field in IPv4, the hop limit field in IPv6 does not specify a maximum number of hops that a packet can traverse in a network. Instead, it specifies the maximum number of routers (hops) that a packet can pass through before it is discarded. This means that the hop limit field does not limit the diameter of the network to a specific number of hops.

The hop limit field in IPv6 also provides some additional benefits over the TTL field in IPv4. For example, it can be used to prevent packets from being forwarded beyond a specific domain or region. Additionally, it allows for better handling of multicast packets, as it can be used to control the propagation of multicast packets in a network.

Therefore, option C is the correct answer as it accurately describes the function of the hop limit field in the IPv6 header.