5 ms·

What's the correct word for "something local that talks to 8.8.8.8/whatever and caches responses" if not recursive? Forwarding?

toast0 7y ago
That's a stub resolver.
JdeBP 7y ago
Forwarding, yes. This terminology is tricky, and the fact that toast0 incorrectly thinks that this is a "stub resolver" is indicative of how people get this stuff wildly wrong. A "stub resolver" is in fact the client that makes requests of the server that you are asking about. I use terminology borrowed from HTTP when explaining this to people. A DNS server that listens on a local IP address and makes back-end queries to another DNS server is a proxy DNS server, and the fact that it hands off all of the grunt work (of stitching together the back-end partial answers to make the front-end complete answers) to another proxy DNS server makes it a forwarding proxy DNS server. If it didn't hand off the grunt work and did all of the query resolution itself, talking directly to content DNS servers, it would be a resolving proxy DNS server. And the software that is in applications, that formulates requests and sends them over to a proxy DNS server, is a DNS client library. 8.8.8.8 is a resolving proxy. * http://jdebp.eu./FGA/dns-server-roles.html http://jdebp.eu./FGA/dns-server-roles.html * http://jdebp.eu./FGA/dns-query-resolution.html http://jdebp.eu./FGA/dns-query-resolution.html * https://unix.stackexchange.com/a/500565/5132 https://unix.stackexchange.com/a/500565/5132
AndyMcConachie 7y ago
Stub resolver: A resolver that cannot perform all resolution itself. Stub resolvers generally depend on a recursive resolver to undertake the actual resolution function. Stub resolvers are discussed but never fully defined in Section 5.3.1 of [RFC1034]. They are fully defined in Section 6.1.3.1 of [RFC1123]. https://tools.ietf.org/html/rfc8499 https://tools.ietf.org/html/rfc8499

toast0 7y ago

That's a stub resolver.

JdeBP 7y ago

Forwarding, yes. This terminology is tricky, and the fact that toast0 incorrectly thinks that this is a "stub resolver" is indicative of how people get this stuff wildly wrong. A "stub resolver" is in fact the client that makes requests of the server that you are asking about. I use terminology borrowed from HTTP when explaining this to people. A DNS server that listens on a local IP address and makes back-end queries to another DNS server is a proxy DNS server, and the fact that it hands off all of the grunt work (of stitching together the back-end partial answers to make the front-end complete answers) to another proxy DNS server makes it a forwarding proxy DNS server. If it didn't hand off the grunt work and did all of the query resolution itself, talking directly to content DNS servers, it would be a resolving proxy DNS server. And the software that is in applications, that formulates requests and sends them over to a proxy DNS server, is a DNS client library. 8.8.8.8 is a resolving proxy. * http://jdebp.eu./FGA/dns-server-roles.html http://jdebp.eu./FGA/dns-server-roles.html * http://jdebp.eu./FGA/dns-query-resolution.html http://jdebp.eu./FGA/dns-query-resolution.html * https://unix.stackexchange.com/a/500565/5132 https://unix.stackexchange.com/a/500565/5132

AndyMcConachie 7y ago

Stub resolver: A resolver that cannot perform all resolution itself. Stub resolvers generally depend on a recursive resolver to undertake the actual resolution function. Stub resolvers are discussed but never fully defined in Section 5.3.1 of [RFC1034]. They are fully defined in Section 6.1.3.1 of [RFC1123]. https://tools.ietf.org/html/rfc8499 https://tools.ietf.org/html/rfc8499