Delivering DNS via IPv6 Router Advertisements

One very cool and highly promoted feature of IPv6 is stateless address autoconfiguration.  If you don’t already know, this feature enables a node to automatically derive its IPv6 address(es) without the help of of a DHCP server.  That is a big departure from the world of IPv4.  In IPv4 you either had to manually configure your IP addresses or you had to use DHCP.  IPv6 has added address autoconfiguration as a third (and typically default) option.

In the earlier days of IPv6 the promise of address autoconfiguration was marred by one unfortunate shortcoming; you still needed to have DHCP servers to give out DNS server infomation (of you had to manually configure it).  For many deployments the only real benefit implementing DHCPv6 was to give out DNS.  And that was just silly.

But all of that is coming to an end.  RFC 6106 (a replacement to RFC 5006) is a proposed Internet standard that will allow routers to advertise DNS server addresses and DNS suffix search order lists.  This is a huge deal.

The router advertisements sent on each IPv6-enabled link used to give routers the ability to announce the network prefixes on the link, whether the router was a gateway for the segment and whether or not DHCP was in use.  Now, with the addition of DNS information, the benefits of address autoconfiguration and router advertisements are largely complete.



Colin Weaver

About the Author

Colin Weaver

Colin Weaver is co-owner and lead instructor at ITdojo, Inc., a network security and information assurance training center and consulting firm located in Virginia Beach, VA. His passion for technology, networks, and security has led him to become enthralled with the idea of IPv6 and its implementation. In this blog he will share with you glimpses of what he has learned and a hint at what you’ll learn in his classes.