We're seeing a weird issue with our DNS resolvers where DNS lookups for .info domains are timing out, but only .info domains. All other GTLD and ccTLD lookups work fine so I doubt it's a fault with the DNS server itself, but I'm wondering if anyone else is seeing the same issue.
In our setup we have a couple of 2012 servers setup to purely run as resolvers (in different physical locations), and which hold no DNS zones (we have separate authoritative servers). Lookups are performed recursively via root hints rather than using any forwarders.
We have monitoring setup which connects to the resolvers and initiates a set of lookup requests to confirm the response matches what we would expect to see, and most of the time everything works fine. Now and again however we'll find that one of the resolvers (it can be either of them, but doesn't tend to be both at the same time) will start failing their montoring tests for .info domains, but not any other domains. If I manually do an nslookup to that server I get the same result, all queries for .info domains time out, all queries for anything else return correct results.
It doesn't matter where the .info is stored either. For instance from our monitoring I check :
mydomain.info (held on our authoritative DNS Server)
myotherdomain.info (held on a 3rd parties DNS Server)
mydomain.net (held on our authoritative DNS Server)
and both .info's fail, but the .net contines to work fine.
It will continue to fail for hours (current time for latest incident is 15 hours), and then eventually recover, but only happens periodically. I've probably seen it happen on and off for months, perhaps even years (on a previous build of the server obviously) but never gotten to the bottom of what's causing it since the infrequency makes diagnosis tricky.