There are a few oddities in Ubuntu’s name resolution code. They mean well, but in my experience don’t always play well with Windows systems, corporate VPNs, etc. Here’s a few changes I make so that all names resolve identically on my Ubuntu systems as they would on my Windows systems. This post is a note to self next time I setup an Ubuntu system.
1. Ununtu 12.04 added dnsmasq into the standard desktop distro, and uses it as the nameserver by default. This is probably a good thing for the majority of users and use cases, but if you’ve either already setup dnsmasq on a system when you upgrade to 12.04, or already run dnsmasq on a central server for the network your 12.04+ system is on, then you might want to get rid of the new dnsmasq that’s embedded in the Ubuntu distro. Fortunately, it’s easy to do: just comment out
dns=dnsmasq
#dns=dnsmasq
in /etc/NetworkManager/NetworkManager.conf.
2. Ubuntu tries to do a magic name resolution of systems within IP-broadcast shouting distance (using Avahi) when the name provided ends in “.local”. As a result, if you’ve actually got names on your network ending in .local that an upstream DNS server is configured to answer, and those hosts aren’t running Avahi or are on the other side of a router, then the name resolution will mysteriously fail. I had to bring in Wireshark to figure out what the hell was going on for this one. The fix, mercifully, is about as easy as the config change in #1 – just tell Avahi to intercept some magic TLD other than “.local” by setting
[server] domain-name=.home
in /etc/avahi/avahi-daemon.conf.
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