Name and Address Lookup for IPv6

It is generally recommended to add IPv6 addresses (known as AAAA records) to a DNS Name Server only when the following conditions are true:

HP recommends beginning with IPv6 addresses and host names in the /etc/hosts file on a development network; then adding IPv6 addresses and hosts to a Domain Name Service when moving IPv6 to a production backbone network.

/etc/nsswitch.conf (nsswitch.conf(4)) is a configuration file for the name service switch. The ipnodes entity specifies which name services resolve IPv4 and IPv6 addresses and host names on HP-UX 11i v1IPv6 bundled as part of TOUR 2.0.

More specifically, on HP-UX 11i v1 IPv6 bundled as part of TOUR 2.0, the ipnodes keyword specifies the resolver policy for the library functions getnameinfo(3N), getaddrinfo(3N), getipnodebyname(3N) and getipnodebyaddr(3N) for both IPv4 and IPv6 addresses. The existing keyword hosts specifies the resolver policy for the library functions gethostbyname() and gethostbyaddr() for IPv4 addresses.

	NOTE: Internet Services applications (such as telnet, r-commands, etc.) use these library functions to resolve IPv4 and IPv6 addresses.

By default, the /etc/nsswitch.conf is not on a system. The default ipnodes policy (same as default hosts policy) is as follows:

dns [NOTFOUND=return] files

This policy implies that dns is the authoritative resolver and will only try files if dns is down. If dns is available but returns NOTFOUND, the search stops.

Thus, if DNS has not been set up as the definitive source, and files (/etc/hosts) may need to be used for address and host name resolution, HP recommends adding the following entry to /etc/nsswitch.conf:

ipnodes: dns [NOTFOUND=continue] files

Or if /etc/hosts is to be the primary Name Service

ipnodes: files [NOTFOUND=continue] dns

	NOTE: You can not specify NIS or NIS+ on the ipnodes entry.

Migrating Name and IPv6 Address Lookup

Most sites test IPv6 on a development subnetwork before deploying it on a larger scale. These sites typically add IPv6 address and host names to the /etc/hosts files on IPv6 hosts, then change their hosts lookup policy to search files.

HP recommends that you maintain at least a minimal /etc/hosts file that includes important addresses like gateways, root servers, and your host’s own IP address. HP also recommends that you include the word files in the hosts and ipnodes lines of /etc/nsswitch.conf to help ensure a successful system boot using the /etc/hosts file when DNS is not available.