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tag: DNS

LinuxSystem Administration

Fixing ip_conntrack Bottlenecks: The Tale Of The DNS Server With Many Tiny Connections

I manage a server which has a sole purpose: serving DNS requests. We use PowerDNS, which has been great. It is a DNS server whose backend is SQL, making administration of large numbers of records very easy. It is also fast, easy to use, open source and did I mention it is free?

The server has been humming along for years now. The traffic graphs don’t show a lot of data moving through it because it only serves DNS requests (plus MySQL replication) in the form of tiny UDP packets.

Read on to follow my story of how I fixed this tricky problem. No kittens were harmed in the writing of this post.

Network Solutions nameservers both appear down. Pings get through occasionally, this may be an indication that they are being DOSed. I used to think that their DNS hosting services would be stable since they were “the” original registrar. But this is the second time in a few months that they’ve been down for a […]