Which of the following commands is used to view whether a voice gateway is registered to an H.323
gatekeeper? (Select the best answer.)

A.
debug isdn q921

B.
debug isdn q931

C.
show ccmmanager

D.
show gateway

Explanation:
The show gateway command is used to view whether a voice gateway is registered to an
H.323 gatekeeper. A gatekeeper is an optional H.323 Voice over IP (VoIP) network devicethat provides access
control, bandwidth management, and other services to H.323 devices on a VoIP network. Although a
gatekeeper is not a required component of an H.323 VoIP network, all H.323 endpoints must register with a
gatekeeper if a gatekeeper exists on the network.
The show gateway command takes no parameters and should be issued in privileged EXEC mode on an H.323
voice gateway. For example, if you were to issue the showgateway command on an H.323 gateway named gw1
that is not registered with an H.323 gatekeeper, you would see the following output:
Gateway gw1 is not registered to any gatekeeper
By contrast, if you were to issue the show gateway command on an H.323 gateway named gw1 that is
registered to an H.323 gatekeeper named gatekeeper1, you would see the following output:
Gateway gw1 is registered to Gatekeeper gatekeeper1
The show ccmmanager command is not used to view whether a voice gateway is registered to an H.323
gatekeeper. The show ccmmanager command displays a list of Cisco Unified Communications Manager
(UCM) servers, the registration status of the servers, and the availability of the servers. For example, you can
issue the show ccmmanager fallbackmgcp command to display the status of a Media Gateway Control Protocol
(MGCP) gateway’s fallback feature. In addition, you can issue the show ccmmanager config-download
command to display the configuration download status of both MGCP gateways and Skinny Client Control
Protocol (SCCP) gateways.
The debug isdn q921 command is not used to view whether a voice gateway is registered to an H.323
gatekeeper. The debug isdn q921 command displays Layer 2 access information about the D channel on
Integrated Services Digital Network (ISDN) connections. The output of the debug isdn q921 command is based
on International Telecommunication Union -Telecommunication Standardization Sector (ITUT)
Recommendation Q.921, which describes ISDN user network interfaces. The debug isdn q921 command
displays Layer 2 information related to transmissions and identity requests. The debug isdn q921 command
displays information from only the D channel because the D channel contains the peertopeer messages
between the router and the called or calling side of the connection.
The debug isdn q931 command is not used to view whether a voice gateway is registered to an H.323
gatekeeper. The debug isdn q931 command displays information about call setup and call teardown on Layer 3
ISDN connections. The output of the debug isdn q931 command is based on the ITUT Recommendation
Q.931, which describes ISDN switching and signaling. The debug isdn q931 command displays information
from only the D channel because the D channel contains the peertopeer messages between the router and the
called or calling side of the connection.

https://www.cisco.com/c/en/us/support/docs/voice/h323/22170-endpoint-admission.html#showGW
https://www.cisco.com/c/en/us/support/docs/voice/h323/5244-understand-gatekeepers.html#gatekeeperdef