We have at the moment about 200 dedicated cpanel servers. Right now, we us on each server bind. This means server1 has ns1 and ns2, server3 has ns3 and ns4.
Now we plan to remove the dns part from the server and build a dns cluster for all our servers. My question is, can 2 dedicated DNSonly Cpanel server handle this amount of dns zones? We talk here about 100000 DNS zones.
How are other hosters (with this amount of servers) handeling the nameservers?
Your biggest bottleneck will be disk IO from what I have seen.
Starting bind or nsd with 100k zones will take a hour+ if the disk io is not up to the task. We have upgraded bind to the latest version as there is some performance speedups, and are utilizing ssd's on DNS only servers doing 50-75k zones.
Its important not to sync all of your zones to all the servers.
In a past life, we had some pretty serious DNS servers - and 6+ years ago, we had well over 700K Zones on them. This was a multi-server setup behind load balancers, that ran at around 8mbit/s of traffic. You do the sums on how busy these servers were, it was not un-common to see upwards of 10k/sec requests which is why they were clustered.
You don't need much space, but to add to what Steven said, you want some decent hardware to do this - fast disk and sufficient RAM
It was a custom set-up running bind and the only time these servers would load all domains up was at server start-up. When I left there, they were actually looking at improving this setup, running a single stealth master for the updates and pushing everything out to the secondaries to serve responses. It was all configured using RNDC and the reload was NEVER used - reconfig is much nicer (and a lot faster)
2 or 3 servers will handle 100K zones - just be careful on how you manage updates to the cluster, and using CPanel DNS Only might not be the best way.
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