What does SLAAC stand for?
SLAAC stands for Stateless Address Autoconfiguration. How an IPv6 host addresses itself without a DHCP server: it takes the network prefix from a router advertisement, builds the interface ID itself and checks for duplicates. Router advertisements can also carry DNS servers (RDNSS); otherwise DHCPv6 supplies them.
SLAAC lets an IPv6 host configure its own address without a DHCP server. The host first gives itself a link-local address, then listens for Router Advertisements. An advertisement carries the network's prefix. The host adds an interface identifier of its own to form a full address and checks, with Duplicate Address Detection, that nobody else on the link is using it. The router that sent the advertisement becomes the default gateway. Stateless means that no server keeps a table of who has which address.
SLAAC in practice: an example
A laptop joins an IPv6 network. Within a second it has an address that begins with the prefix the router announced, 2001:db8:1:20::/64, and a default route, although the network has no DHCPv6 server. The address of the DNS server arrives in the same Router Advertisement, as an option the router includes.
What SLAAC is confused with
SLAAC vs DHCPv6: what is the difference?
DHCPv6 is a server assigning addresses or handing out settings and, in its stateful form, recording who has what. With SLAAC the host builds its own address from the router's prefix. Networks can combine them: SLAAC for the address, DHCPv6 for the other settings.
SLAAC vs APIPA: what is the difference?
APIPA is an IPv4 fallback that produces a link-local address with no route to anywhere. SLAAC is a normal way to obtain a routable IPv6 address. What APIPA stands for
Which exams cover SLAAC?
SLAAC is on the official CompTIA acronym list for one of the four exams covered here.
- Network+ N10-009: 3.0 (Network Operations).
Each number is a CompTIA exam objective and the name in brackets is its domain. The exam puts the term in a scenario; it does not ask you to recite the expansion.
Check yourself: two practice questions
Written by CertSprint for this page. They are not taken from any exam.
1. An IPv6 host builds its global address from a prefix it learned on the network. Which message carried the prefix?
- A Router Advertisement
- A DHCP Offer
- An ARP reply
- A DNS response
Show the answer
A. A Router Advertisement. Routers announce the prefix in ICMPv6 Router Advertisements. SLAAC hosts combine it with an interface identifier of their own.
2. Why does a host using SLAAC perform Duplicate Address Detection?
- To make sure no other node on the link already uses the address
- To encrypt the address
- To register the address with a DHCP server
- To discover the DNS server
Show the answer
A. To make sure no other node on the link already uses the address. The host chose the address itself, so nothing guarantees that it is unique. It asks the link whether anyone already has it before using it.
Sources: RFC 4862: IPv6 Stateless Address Autoconfiguration; RFC 4861: Neighbor Discovery for IP version 6 (IPv6); RFC 8106: IPv6 Router Advertisement Options for DNS Configuration. The acronym and its expansion come from CompTIA's official acronym lists, linked from each exam glossary above. The explanation, example and questions are CertSprint's own, checked against these sources on 12 November 2026.