Forum Discussion
GTM DNS ReverseLookup
Hello everyone!!
I was curious as to how the GTM gslb functions when executing a reverse lookup. I have a gslb url that fetches two ltm vips when I perform a nslookup, but when I try to perform a reverse lookup on the IP received, nothing like a failed result appears.
Is this the gslb via GTM default behavior? or something not configured as is?
- Leslie_HubertusRet. Employee
Hey ashk - I see nobody has answered this yet. I'll pin this to the top of the forum over the weekend to give your question better visibility.
- KerryCirrus
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.
- Siona_SombobaNimbostratus
seems like DNS "A" records missing for the 2 VS IP addresses in local DNS. please add and test
if not please share output
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