Where do software query reverse IP ?

[ECO]

  Let's suppose we have :
- a nameserver, ns1, authoritative for the domain example.com.
- www.example.com. A 192.168.1.1   ; And the reverse also...
  
  Some software after an A lookup do a reverse query to verify whether the
IP address matches the name or not.
  My question is : Will the software do a reverse query on ns1 for the IP
192.168.1.1 as it found ns1 to be the master DNS server of
(www.)example.com ?