Comment 3 for bug 584910

Try this that has been working for me when I added a name (in /etc/hosts host's file) to the IP used by the guess: $ sudo kill -HUP `pidof dnsmasq`

Howerver I get a different (related trouble): custom host definition is not honor with my configuration (even after rebooting the host). dnsmasq give a adress from the dhcp range to my VM.
Here is my config /etc/libvirt/qemu/networks/default.xml
<network>
  <name>default</name>
  <bridge name="virbr%d" />
  <forward/>
  <ip address="192.168.122.1" netmask="255.255.255.0">
    <dhcp>
      <range start="192.168.122.100" end="192.168.122.239" />
      <host mac="52:54:00:bf:0f:d0" name="test" ip="192.168.122.10" />
    </dhcp>
  </ip>
</network>

sudo grep 52:54:00:bf:0f:d0 /etc/libvirt/qemu/*.xml
/etc/libvirt/qemu/test.xml: <mac address='52:54:00:bf:0f:d0'/>

Do you have any idea that may explain why this doesn't work ?