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