Once you have configured the Eureka service as described in this section, it will be available for all incoming requests so that they're listed there. The Eureka service registers/lists all microservices that have been configured by the Eureka client. Once you start your service, it pings the Eureka service configured in your application.yml file, and once a connection is established, the Eureka service registers the service.
Eureka service also enables the discovery of microservices through a uniform way to connect to other microservices. You don't need an IP, hostname, or port to find the service; you just need to provide the service ID to it. Service IDs are configured in the application.yml file of the respective microservices.
Netflix Eureka Server stores all information in memory. In fact, Eureka Server is also a Eureka client, which is required to ping peer Eureka Servers that are defined using the service URI. Peer Eureka Servers are required in high-availability zones and regions. However, if you don't have a peer Eureka Server, you can simply run it using standalone mode by changing its configuration. We'll cover this in the third step of the Implementation section.