[davchana]

Dns is like a big phone book with domain & its host server's ip address, all dns servers around the world routinely & frequently copy each other's changes & updates, but the additions & changes originate in TLD Owner's zone file, a master phone book for that TLD, & then it propagates to other world.

A registrar takes your money & coordinates with TLD owner to add your domain to the master phone book. In about x time, minutes to hours to few days, all servers over the world has your domain's dns information. Most of the time registrar's job is done, & now hosting provider as well as dns servers come in picture.

Now, when a user types your domain, his internet provider or dns address server looks up the relevant ip & or ask around. Closest/fastest/reliable records are then used. Your registrar usually do not control or operate these servers, but Google 8.8.4.4, Cloud flare 1.1.1.1, your ISP & such operate these.

The geographic closeness to hosting servers is preferred, but I think geographic closeness to register doesn't matter much.