I'm learning about DNS and have a very basic, generic question about DNS but I can't find an answer anywhere.
I have DNS for a few domains set up as follows: - master records with DNS company A - slave records with DNS company B
Company A's nameservers are:
ns1.companyA.com.
ns2.companyA.com.
ns3.companyA.com.
ns4.companyA.com.
ns5.companyA.com.
and company B has three slaves:
ns6.companyB.com.
ns7.companyB.com.
ns8.companyB.com.
Everything works fine transferring the records between the nameservers and keeping them in sync.
But my question is: The registrar of my domain example.com allows me to choose 4 nameservers only. Do I just pick the first 4 for company A, or do I need to include 1 or more of company B's slave nameservers too?
The NS records you supply to the registrar should be as network diverse as possible. The reason for that is if one network goes down then some other name server on another network should still be up.
Presumably, all name servers from company A are on one network and all from company B would be on another network. If that's the case choose two from each.
If company A's name servers are on two networks and company B's name servers are on two networks (making 4 in total) then use one from each.