GTM DNS ReverseLookup

Forward and reverse looks have nothing to do with each other.   If luck the F5 GUI might add a record, but it does not mean things will work.  Have a look under

forward lookup:  DNS> zone>zonerunner>resource records: view = external (unless you use split DNS),  names = FQDN domain, type=a/aaaa , names = host name/Wide IP names.      you should see "0" TTL records if the Wide IP is defined. 

forward lookup  DNS> zone>zonerunner>>resource records: view = external (unless you use split DNS),  names = ...in-addr-arpa.   you see PTR type records if things are defined.   RDATA = FQDN. 

dig/nslookup   FQDN F5-ip to test forward   - i.e. nslookup f5.com 8.8.8.8 

dig/nslookup  q=ptr (IP address in reverse).in-addr-arpa.  F5-ip to test reverse 

i.e. nslookup -q=ptr 40.162.162.107.in-addr.arpa 8.8.8.8    (might have the incorrect syntax here)

For forward lookup the domain above you need to define you as a subdomain using NX records.    Same for reverse but is probably your IPS or who you got the IP address from is the DNS holder.  I think you need a BGP AS number for this setup.   i.e F5 the owner of  *.162.107.in-addr.arpa  would need to define NX record for “162” then then in thay zone can the PRT recodes be defined.

I assume you talking about public DNS and not a private DNS.