Comment 3 for bug 1507834

Hey there. I've got exactly the same issue:

Log message:
2016-02-14T01:09:55.518748Z qemu-system-x86_64: -vnc [ipv6addr]:0: Failed to start VNC server on `(null)': address resolution failed for [ipv6addr]:5900: Temporary failure in name resolution

Ubuntu 15.10

ii ipxe-qemu 1.0.0+git-20141004.86285d1-1ubuntu3 all PXE boot firmware - ROM images for qemu
ii qemu-block-extra:amd64 1:2.3+dfsg-5ubuntu9.2 amd64 extra block backend modules for qemu-system and qemu-utils
ii qemu-slof 20140630+dfsg-1ubuntu1 all Slimline Open Firmware -- QEMU PowerPC version
ii qemu-system 1:2.3+dfsg-5ubuntu9.2 amd64 QEMU full system emulation binaries
ii qemu-system-arm 1:2.3+dfsg-5ubuntu9.2 amd64 QEMU full system emulation binaries (arm)
ii qemu-system-common 1:2.3+dfsg-5ubuntu9.2 amd64 QEMU full system emulation binaries (common files)
ii qemu-system-mips 1:2.3+dfsg-5ubuntu9.2 amd64 QEMU full system emulation binaries (mips)
ii qemu-system-misc 1:2.3+dfsg-5ubuntu9.2 amd64 QEMU full system emulation binaries (miscelaneous)
ii qemu-system-ppc 1:2.3+dfsg-5ubuntu9.2 amd64 QEMU full system emulation binaries (ppc)
ii qemu-system-sparc 1:2.3+dfsg-5ubuntu9.2 amd64 QEMU full system emulation binaries (sparc)
ii qemu-system-x86 1:2.3+dfsg-5ubuntu9.2 amd64 QEMU full system emulation binaries (x86)
ii qemu-utils 1:2.3+dfsg-5ubuntu9.2 amd64 QEMU utilities

and

ii libvirt-bin 1.2.16-2ubuntu11.15.10.3 amd64 programs for the libvirt library
ii libvirt0 1.2.16-2ubuntu11.15.10.3 amd64 library for interfacing with different virtualization systems
ii nova-compute-libvirt 2:12.0.0-0ubuntu2 all OpenStack Compute - compute node libvirt support
ii python-libvirt 1.2.15-0ubuntu1 amd64 libvirt Python bindings

Hope this helps