How is authentication arranged when there are more than 1 servers?

Question

Django

Hello.
Please help me figure out how authentication works in the case of multiple servers.
For example, let's take jwt token authentication and django. If I understand correctly, then on registration/login, the token is issued by the authentication "module" that comes with django. Further, this token is stored on the client, and with each subsequent request it is sent to the server, the server, using the same authentication "module", checks this token, and if everything is fine, then the request is executed. At least it seems to me that it works like this, further reasoning based on the above.
Now, let's say, let's take Instagram, which was originally made on jang. He has a bunch of servers like this with janga, between which requests are distributed to cope with the load, because one server cannot quickly process such a huge number of requests. Let's say it's 100 servers. I register on Instagram and get to the server number 54, which gives me a token. Question: now only server #54 can check this token and all my interaction with Instagram will take place through server #54 (until the token is reissued by another server)?

Answer 1

All servers know the key with which the token is encrypted, so any server can check its validity.

Answer 2

We read about OAuth2, OpenId, what Identity Server is and get out of our heads that this is part of the project. And, more about Single Sign-on (SSO)