Which service provides network information for IPv6 SLAAC addressing?

Which of the following services provides the network information for the address when IPv6 is used for SLAAC addressing?

EUI-64
IPv6 unicast routing
Router advertisement Source Reference Answer
DHCPv6

Community Votes

75%

25%

75% of anonymous learners picked answer C. Votes are pick records left by other test-takers — they are not the verified answer.

Community Insight

The question tests whether you know SLAAC relies on Router Advertisements for the network prefix, not on EUI-64, which only generates the host portion of the address.

In IPv6 SLAAC, Router Advertisement (RA) messages provide the network prefix and routing information hosts need to generate their addresses. The community consensus is that Option C is correct, while EUI-64 is often confused but only creates the interface identifier.

The most common wrong answer is A. EUI-64, because test takers remember EUI-64 is involved in SLAAC but forget it only generates the interface ID, not the network information.

Community Discussion (5 comments)

subaie503 👍 1 Selected: C

C. Router advertisement Router advertisement is part of the Neighbor Discovery Protocol (NDP) in IPv6 and is used in Stateless Address Autoconfiguration (SLAAC) to provide network information to IPv6 hosts. Router advertisements inform hosts about the presence of routers, network prefixes for address configuration, and various other parameters necessary for the host to configure its IPv6 address and connect to the IPv6 network. This mechanism allows IPv6 devices to automatically configure themselves with an IPv6 address and other related network information without the need for a DHCPv6 server, although DHCPv6 can be used alongside SLAAC for additional configuration options like DNS server addresses.

72abe44 👍 2

C is correct. From Cisco: SLAAC provides the ability to address a host based on a network prefix that is advertised from a local network router via Router Advertisements (RA). RA messages are sent by default by most IPV6 routers; these messages are sent out periodically by the router and include information including: - One or more IPv6 prefixes (Link-local scope) - Prefix lifetime information - Flag information - Default device information (Default router to use and its lifetime)

PatrickH 👍 2 Selected: C

SLAAC. IPv6 hosts configure themselves automatically. Every interface has a self-generated link-local address and, when connected to a network, conflict resolution is performed and routers provide network prefixes via router advertisements. So its C

Popeyes_Chicken 👍 3 Selected: C

C. Router advertisement Router advertisement messages are used in IPv6 networks to advertise routing information, including network prefixes, to hosts. When SLAAC is used, routers send router advertisement messages periodically, informing hosts about the network's prefix, which the hosts then use to generate their IPv6 addresses. This process allows hosts to configure their own IPv6 addresses without the need for a DHCPv6 server.

Pisces225 👍 2 Selected: A

The prefix for all link-local addresses is fe80::/64. The interface identifier (or last 64 bits from left to right) of the address is typically auto-generated by using the modified EUI-64 method (RFC 4291). DHCPv6 is the opposite of SLAAC. SLAAC precludes the use of DHCPv6. You use one or the other, not both. The entire point of SLAAC is so you don't have to use DHCPv6.

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Expert Analysis

Why the Answer Is Correct

SLAAC (Stateless Address Autoconfiguration) uses Router Advertisement (RA) messages sent by IPv6 routers to provide the network prefix to hosts. These RA messages, part of Neighbor Discovery Protocol (NDP), include the prefix, prefix lifetime, and default router information, allowing hosts to create their full IPv6 address. The correct answer is therefore C, Router advertisement.

Why the Other Options Are Wrong

EUI-64 (A) is not a service but a method for generating the interface identifier (the lower 64 bits) from the MAC address; it does not provide network information. IPv6 unicast routing (B) is a general routing function, not a specific address autoconfiguration service. DHCPv6 (D) can provide address and other configuration but is not used in pure SLAAC—SLAAC is designed to allow hosts to self-configure without DHCPv6. Thus only C correctly describes the service that supplies the network prefix.

Community Comment Notes

Commenters overwhelmingly support C, correctly noting RA messages advertise the network prefix for SLAAC. A comment choosing A shows the common confusion: it mentions EUI-64 generates the interface identifier, but that is only the host part—the network information comes from RA. Other comments reference the Cisco explanation that RA messages by default include IPv6 prefixes and prefix lifetime information, reinforcing why C is the right answer.

Official Reference

Exam Strategy

On CompTIA Network+ exams, remember that SLAAC is a two-step process: the router advertises the prefix via RA, and the host uses EUI-64 or a random value to create the interface ID. If a question asks 'what provides the network information,' look for Router Advertisement—not EUI-64, which only builds the host portion.

Related Analysis

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