By default,according to k8s documentation, Services are assigned a DNS A record for a name of the form my-svc.my-namespace.svc.cluster-domain.example.
Is there a command to retrieve the full name of a service?
You can do a DNS query from any pod and you would get the FQDN.
# nslookup api-server
Server: 10.96.0.10
Address: 10.96.0.10#53
Name: api-server.default.svc.cluster.local
Address: 10.104.225.18
root@api-server-6ff8c8b9c-6pgkb:/#cluster-domain.example is just a example in the documentation. cluster.local is the default cluster domain assigned. So the FQDN of any service by default would be <service-name>.<namespace>.svc.cluster.local.
You don't need to use the FQDN to access services - for services in same namespace, just the service name would be enough. For services in other namespaces, <service-name>.<namespace> would be enough as kubernetes would automatically set up the DNS search domains.