I don't believe resolv.conf is in any DNS RFC individually. Here's a list of all RFCs related to DNS: https://www.isc.org/community/rfcs/dns/ https://www.isc.o

I don't believe resolv.conf is in any DNS RFC individually. Here's a list of all RFCs related to DNS: https://www.isc.org/community/rfcs/dns/ https://www.isc.org/community/rfcs/dns/ In https://tools.ietf.org/html/rfc1034 https://tools.ietf.org/html/rfc1034 this is discussed: The resolver always starts with a list of server names to query (SLIST). This list will be all NS RRs which correspond to the nearest ancestor zone that the resolver knows about. To avoid startup problems, the resolver should have a set of default servers which it will ask should it have no current NS RRs which are appropriate. The resolver then adds to SLIST all of the known addresses for the name servers, and may start parallel requests to acquire the addresses of the servers when the resolver has the name, but no addresses, for the name servers. I believe it would be an accurate statement that a DNS resolver which is incapable of servicing all DNS queries by the client is something which many clients are not designed to expect. But relying on the behavior of glibc in the way it attempts lookups is in essence relying on the internal workings of that software rather than anything written in the spec. BIND9 supports 'views' (iirc) which allow for splitting queries between internal vs. external DNS. But that would be the resolver as opposed the users desktop implementing that.