On desktops this is Network Manager. On 12.04 Server there is no Network Manager but the package resolvconf is still installed.
Originally Posted by surfer
The resolvconf app creates the /etc/resolv.conf file dynamically. It uses the data in the /etc/network/interfaces file (i.e.dns-nameservers) for the DNS name server IP addresses on a Ubuntu 12.04 Server with static IP addressing.
2. what script creates the resolv.conf symlink (pointing to ../run/resolvconf/resolv.conf)? can i call that script manually?
3. on a FAI install of a client, i saw that tere is no /run/resolvconf/resolv.conf file (the directory exists). what script puts that file there?
4. are there more questions about the new resolv.conf handling i forgot to ask?
Note: there are other locations that can hold hooks to the information if using DHCP or other dynamic IP addressing.
From the resolvconf man page
Normally resolvconf is run only by hook scripts attached to network
interface configurers such as pppd(8) (for ppp interfaces), to DHCP
clients such as dhclient(8), to ifup(8) and ifdown, and to DNS caches
such as dnsmasq(8) (for the loopback interface). These hook scripts
furnish resolvconf with information about nameservers.