Which two statements are true when configuring a domain-id? ()
A、A. The default OSPF domain-id is 127.0.0.1.
B、B. In most cases, a domain-id must be configured.
C、C. In most cases, you do not need to configure a domain-id.
D、D. For a layer 3 VPN connecting multiple OSPF domains, configuring a domain-id can help control LSA translations.