Last Updated on November 16, 2023 by InfraExam
What two ICMPv6 message types must be permitted through IPv6 access control lists to allow resolution of Layer 3 addresses to Layer 2 MAC addresses? (Choose two.)
- echo requests
- router solicitations
- router advertisements
- neighbor advertisements
- echo replies
- neighbor solicitations
|Explanation & Hint:
In IPv6, to allow the resolution of Layer 3 addresses (IP addresses) to Layer 2 addresses (MAC addresses), certain ICMPv6 (Internet Control Message Protocol version 6) message types are essential. These messages are part of the Neighbor Discovery Protocol (NDP), which is used in IPv6 networks for various purposes, including address resolution. The two specific ICMPv6 message types that must be permitted through IPv6 access control lists (ACLs) for this purpose are:
- Neighbor Solicitations: These messages are used by a node to determine the link-layer address (MAC address) of a neighbor, or to verify that a neighbor is still reachable via a cached link-layer address. Neighbor Solicitations are essentially the IPv6 equivalent of ARP requests in IPv4.
- Neighbor Advertisements: These are the responses to Neighbor Solicitations. A node sends a Neighbor Advertisement to announce or confirm its link-layer address to other nodes. It is analogous to an ARP reply in IPv4.
The other ICMPv6 message types you mentioned serve different purposes:
- Echo Requests and Echo Replies: These are used by the Ping utility to test reachability in a network. While important for diagnostic purposes, they are not specifically used for address resolution.
- Router Solicitations and Router Advertisements: These are part of the NDP but are used for the discovery of routers and the acquisition of various configuration settings, not for address resolution between Layer 3 and Layer 2.
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