NIC card DNS settings for IdM with Integrated DNS

A question about best practices:

I remember having been taught in school many years ago that when you set up a Windows domain controller and DNS you would point the DNS settings on the NIC to itself. I presume the same would hold true for Linux. By all means correct me if I am wrong!

I presently have 2 IdM servers that I inherited:
ipa1 x.x.1.10
ip2 x.x.1.11

However the DNS on the NIC is set to :
ipa1
DNS x.x.1.11 (ipa2)

ip2
DNS x.x.10.10 (windows AD)

This seems very inconsistent. I would think the settings should be:
ipa1
DNS x.x.x.10 (ipa1)

ipa2
DNS x.x.x.11 (ipa2)

I know you could make the argument that they should have 2nd entries for each other but this would be the very minimum that should be set properly. Can anyone offer insights or corrections on my assumptions? I couldn't find any documentation to deal with this specific issue. Thanks!