every DNS resolver starts with a root nameserver

Illustration of a conversation between a resolver, represented by a box with a smiley face holding a magnifying glass, and a root nameserver, represented by a box with a smiley face wearing a stack of crowns.

resolver: what’s the IP for example.com?
root nameserver: You should ask a .com nameserver! They’re at a.gtld-servers.net, b....

root nameserver IP addresses almost never change

a.root-servers.net’s IP (198.41.0.4) hasn’t changed since 1993. DECADES ago!

there are thousands of physical root nameservers, but only 13 IP addresses

Each IP refers to multiple physical servers, you’ll get the one closest to you. (this is called “anycast”)

There’s a map at https://root-servers.org

if they didn’t exist, resolvers wouldn’t know where to start

resolver, distressed: I need an IP address of an initial server to query, and I can’t use DNS to get that IP!

every resolver has the root IPs hardcoded in its source code

example: https://wzrd.page/bind

You can query one like this:
dig @198.41.0.4 example.com

All the IPs will give you the exact same results, there are just lots of them for redundancy.

Here they are!

a.root-servers.net 198.41.0.4   
b.root-servers.net 199.9.14.201 
c.root-servers.net 192.33.4.12 
d.root-servers.net 199.7.91.13 
e.root-servers.net 192.203.230.10 
f.root-servers.net 192.5.5.241 
g.root-servers.net 192.112.36.4
h.root-servers.net 198.97.190.53
i.root-servers.net 192.36.148.17
j.root-servers.net 192.58.128.30
k.root-servers.net 193.0.14.129
1.root-servers.net 199.7.83.42
m.root-servers.net 202.12.27.33