You implement multiple registrars for SIP Trunks for the Cisco Unified Border Element to ensure redundant PSTN access, you receive an error that indicates that the registration server is invalid. Which two commands correct the problem? (Choose two)
A. Registrar 2 ipv4:1.1.1.1 expires 360
B. CUSP registrar 9 dns:cisco.com expires 60
C. No registrar 2 dns:cisco.com expires 60
D. Registrar 20 dns:cisco.com
E. Registrar 1 dns:cisco.com expires 180
https://www.cisco.com/c/en/us/td/docs/ios-xml/ios/voice/sip/configuration/15-mt/sip-config-15-mt-book/voi-sip-multi-trunks.html