How Do PTR Lookups Work with IP Addresses?
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TechNinja42
Hey everyone! I have a question about how PTR lookups work. When I run an nslookup for one of my public IP addresses from my home computer, I'm curious about how my home ISP's DNS servers perform that lookup to return a DNS name. With A record lookups, it's straightforward since the DNS server can contact the authoritative name server for the host name. But how does a DNS server know which server to ask for IP-to-host name resolutions?
Answers
So, about PTR lookups—there are reverse DNS servers that handle this with .arpa TLDs. The organization that owns an IP block sets up a server for the addresses in that range.
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TechNinja42: That’s interesting! But how does it then map to a specific host name? My ASN that controls my IP block doesn’t actually have info about my host names. Also, if I wanted to remove a PTR record, how would I manage that? I can easily remove an A record in Cloudflare, but do they allow management of PTR records too? And how can I see more details on how nslookup resolves a PTR lookup?