Compare DNS zone on two different DNS servers

 diff <(sort -u <(dig +nottlid +noall +answer @10.0.0.10 example.com TXT -t axfr) ) <(sort -u <(dig +nottlid +noall +answer @10.0.0.11 example.com TXT -t axfr) )

Works in bash

Query txt records with nslookup:

set q=txt
c3po._domainkey.altn.com