How does using DNS seeds to find initial peers compare to using seednode?

Question

How does using DNS seeds to find initial peers compare to using -seednode?

This was asked by prayank on IRC and has been paraphrased.

A related question is here.

Answer 1

This was answered by dhruv and sipa on IRC.

-seednode: a peer node that is only asked to respond to GETADDR.

(This is the bootstrapping mechanism used for Tor nodes.)

DNS seeds are names that resolve to the IP addresses of good full nodes. The set of IP addresses you get back changes all the time.

Unproxied Internet access + DNS seeds => One domain name resolves to many IPs that go into addrman

Proxied internet access + DNS seeds => One domain name resolves to one IP that acts like a -seednode.

The related Bitcoin Core code is here. git grep for CConnman::ThreadDNSAddressSeed()