How to check for the existence of deep subdomains even if the intermediate ones don't exist?
Dec 31
Suppose that test.example.com don't exists and gives NXDOMAIN when runnning dig on it , but i know that subdomain.test.example.com exists and gives NOERROR when doing the same, is there a way to check that a deep subdomain exists even though the intermediate subdomain may not be there necessarily. Specifically, I'm looking for hints when probing or querying subdomain.test.example.com that points to the existance of the deep subdomain?
1 answer
Accepted answer · original discussion
Dec 31
Suppose that test.example.com don't exists and gives NXDOMAIN when runnning dig on it , but i know that subdomain.test.example.com exists
This is not possible, per DNS specifications. Or said differently: it means the authoritative nameserver for this zone is broken.
See RFC 8020: NXDOMAIN: There Really Is Nothing Underneath
When an iterative caching DNS resolver receives an NXDOMAIN response, it SHOULD store it in its cache and then all names and resource record sets (RRsets) at or below that node SHOULD be considered unreachable. Subsequent queries for such names SHOULD elicit an NXDOMAIN response.
0 question comments
Use comments to ask for clarification. Post a solution as an answer.
No question comments on this page.