What exactly is AVAHI?

CentOS 5.2

My VPS host rebooted (checking with host support now) and I noticed the following in /var/log/messages

Aug 28 11:57:52 echo avahi-daemon[21633]: **Found user 'avahi' (UID 70) and group 'avahi' (GID 70).**
Aug 28 11:57:52 echo avahi-daemon[21633]: **Successfully dropped root privileges.**
Aug 28 11:57:52 echo avahi-daemon[21633]: **avahi-daemon 0.6.16 starting up.**
Aug 28 11:57:52 echo avahi-daemon[21633]: WARNING: No NSS support for mDNS detected, consider installing nss-mdns!
Aug 28 11:57:52 echo avahi-daemon[21633]: dbus_bus_get(): Failed to connect to socket /var/run/dbus/system_bus_socket: No such file or directory
Aug 28 11:57:52 echo avahi-daemon[21633]: WARNING: Failed to contact D-Bus daemon.
Aug 28 11:57:52 echo init: no more processes left in this runlevel

What exactly is avahi? Is this a standard message?

From serverfault Mikey B

• Avahi is a system which facilitates service discovery on a local network via the mDNS/DNS-SD protocol suite. More information here.

  Mikey B : Thanks. Is it installed by default? I'm not sure why it's on my VPS server... can/should it be disabled on servers? If so, how can this be done?

  Raphink : I don't think it's necessary to have avahi running on a server. I personally never install it (even on desktops). Service discovery is not necessary on a well set network with servers: I'm guessing all your servers must have static IPs, you have a DNS server with DNS entries for each server, and you probably know what services each server provides (hopefully).
  From Iain

• As Iain said Avahi provides similar functionality to Bonjour or Rendezvous for Linux. On a server I really don't see a need for it... I've turned it off myself on servers I've setup.

  You can stop the service and then turn it off at boot using these two commands:

  service avahi-daemon stop 
  chkconfig avahi-daemon off
  

  From Eric Gearhart