Hi - I've been running into somewhat inconsistent behavior with DNS short name resolution in Debian across a few systems.
Here's the behavior that I've occasionally relied on over the years: % cat /etc/resolv.conf search example.com nameserver 192.0.2.10 % host foo.bar.baz.example.com. foo.bar.baz.example.com has address 192.0.2.1 foo.bar.baz.example.com has IPv6 address 2001:db8::1 % host foo.bar.baz foo.bar.baz.example.com has address 192.0.2.1 foo.bar.baz.example.com has IPv6 address 2001:db8::1 Basically, I expect the search suffix to always be appended to the label unless a trailing "." (ie, fully-qualified) is the last character. I don't know if it was a glibc upgrade or something else but on a few of my Debian systems (combination of i386 and x86_64) I now cannot resolve any short names that have a dot in them. So, the above example now returns: % cat /etc/resolv.conf search example.com nameserver 192.0.2.10 % host foo.bar.baz.example.com. foo.bar.baz.example.com has address 192.0.2.1 foo.bar.baz.example.com has IPv6 address 2001:db8::1 % host foo.bar.baz Host foo.bar.baz not found: 3(NXDOMAIN) However, something this will still succeed: % host www www.example.com has address 192.0.2.2 www.example.com has IPv6 address 2001:db8::2 Running tcpdump and filtering on port 53 confirms what I'm seeing above—the resolver just isn't appending the search prefix to names with a dot in them. I've run into this issue on Mac OS X and Windows and in each case there were [possibly hacky] tweaks to restore the legacy behavior. I don't use these short names too often so I can't pinpoint when this broke or what I upgraded to change this behavior. I don't use any DNS-related options in /etc/network/interfaces and I don't have mDNSResponder or any local caching resolver running. I realize that using short names in this fashion may be not the best thing to do anymore considering recent ICANN policies and the plethora of new TLDs. However, I'd like to still have the option to enable this behavior. Any ideas? Thanks! - Mark -- Mark Kamichoff p...@prolixium.com http://www.prolixium.com/
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