On a fresh boot, 'ping host.local' does not work. This is because avahi-daemon is not running. However, if the daemon is started manually through e.g. /etc/init.d/avahi-daemon start then things work just fine and 'ping host.local' works as expected. And it seems like avahi-daemon is automatically started when needed in this case. So it could be a systemd or D-Bus system bus activation bug, I don't know.
Here are some more details - from a fresh boot: [root@x61 ~]# ping phobos.local ping: unknown host phobos.local [root@x61 ~]# ps aux|grep avahi-daemon root 1946 0.0 0.0 103424 880 pts/1 S+ 12:54 0:00 grep --color=auto avahi-daemon [root@x61 ~]# systemctl status avahi-daemon.service avahi-daemon.service - Avahi mDNS/DNS-SD Stack Loaded: loaded (/lib/systemd/system/avahi-daemon.service) Active: inactive (dead) CGroup: name=systemd:/system/avahi-daemon.service Note how it doesn't automatically get launched [root@x61 ~]# systemctl start avahi-daemon.service [root@x61 ~]# ping phobos.local PING phobos.local (10.200.0.101) 56(84) bytes of data. 64 bytes from phobos-eth1.home.fubar.dk (10.200.0.101): icmp_req=1 ttl=64 time=0.911 ms 64 bytes from phobos-eth1.home.fubar.dk (10.200.0.101): icmp_req=2 ttl=64 time=0.240 ms ^C --- phobos.local ping statistics --- 2 packets transmitted, 2 received, 0% packet loss, time 1001ms rtt min/avg/max/mdev = 0.240/0.575/0.911/0.336 ms [root@x61 ~]# systemctl status avahi-daemon.service avahi-daemon.service - Avahi mDNS/DNS-SD Stack Loaded: loaded (/lib/systemd/system/avahi-daemon.service) Active: active (running) since Tue, 22 Mar 2011 12:54:44 -0400; 12s ago Main PID: 1978 (avahi-daemon) Status: "Server startup complete. Host name is x61.local. Local service cookie is 2243943552." CGroup: name=systemd:/system/avahi-daemon.service ├ 1978 avahi-daemon: running [x61.local] └ 1979 avahi-daemon: chroot helper [root@x61 ~]# systemctl stop avahi-daemon.service [root@x61 ~]# systemctl status avahi-daemon.service avahi-daemon.service - Avahi mDNS/DNS-SD Stack Loaded: loaded (/lib/systemd/system/avahi-daemon.service) Active: inactive (dead) since Tue, 22 Mar 2011 12:55:18 -0400; 2s ago Process: 1998 ExecStart=/usr/sbin/avahi-daemon -s (code=exited, status=0/SUCCESS) Status: "avahi-daemon 0.6.29 exiting." CGroup: name=systemd:/system/avahi-daemon.service But now it automatically gets launched (as expected) ... [root@x61 ~]# ping phobos.local PING phobos.local (10.200.0.101) 56(84) bytes of data. 64 bytes from phobos-eth1.home.fubar.dk (10.200.0.101): icmp_req=1 ttl=64 time=0.274 ms 64 bytes from phobos-eth1.home.fubar.dk (10.200.0.101): icmp_req=2 ttl=64 time=0.303 ms ^C --- phobos.local ping statistics --- 2 packets transmitted, 2 received, 0% packet loss, time 1001ms rtt min/avg/max/mdev = 0.274/0.288/0.303/0.022 ms [root@x61 ~]# systemctl status avahi-daemon.service avahi-daemon.service - Avahi mDNS/DNS-SD Stack Loaded: loaded (/lib/systemd/system/avahi-daemon.service) Active: active (running) since Tue, 22 Mar 2011 12:55:27 -0400; 2s ago Main PID: 2006 (avahi-daemon) Status: "Server startup complete. Host name is x61.local. Local service cookie is 665919058." CGroup: name=systemd:/system/avahi-daemon.service ├ 2006 avahi-daemon: running [x61.local] └ 2007 avahi-daemon: chroot helper
It's probably not enabled. Can you do "systemctl enable avahi-daemon.service"? Do things work then for you? If you start avahi-daemon.service this will pull in the avahi-daemon.socket too. If you then terminate the former, the latter will stay on however, hence socket activation via name resolution still succeeds. Anyway, the fact that it isn't enabled anymore by default is tracked in bug 647831 *** This bug has been marked as a duplicate of bug 647831 ***