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?