2 DNS Entries, Multiple Servers

Question

At the moment we have:

ns1.example.com -> dns1
ns2.example.com -> dns2

I was wondering if it was possible to do something like this:

ns1.example.com -> dns1, dns3, dns5
ns2.example.com -> dns2, dns4, dns6

I am attempting to set up a round robin, fault resistant setup with as little hops as possible.

Answer 1

DNS is redundant by design.

Adding what you think is additional redundancy doesn't actually help.

Answer 2

Yes, it's possible to do this:

ns1.example.com -> dns1, dns3, dns5
ns2.example.com -> dns2, dns4, dns6

by having multiple A records for each of ns1 and ns2.

However you might as well do this:

ns1.example.com. IN A ...
   ...
ns6.example.com. IN A ...

which should give you more even distribution of queries across the six servers.

Answer 3

If you want to add more name servers just add more NS records. They will be served up in a round robin fashion by default. Unless you have lots of traffic two or three name servers should be sufficient. Most requests will be served from cache if you have much traffic.

If you have the kind of traffic that Google, Amazon, or Facebook have you should have technical staff who know how to optimize DNS for fast server access.