Refer to the H.323 message in the exhibit. What is the gateway doing with the gatekeeper?

A.
initial registration

B.
full registration

C.
lightweight registration

D.
registration retry

Explanation:
For the first time the gateway registers with the gatekeeper, it uses full registration. Prior to H.323 Version 2, Cisco gateways re-registered with the gatekeeper every 30 seconds. Each registration renewal used the same process as the initial registration, even though the gateway was already registered with the gatekeeper. This behavior generated considerable overhead at the gatekeeper. So from H.323 version 2, gateways can re-register with the gatekeeper using lightweight registration (it still requires the full registration process for initial registration, but uses an abbreviated renewal procedure to update the gatekeeper and minimize overhead).

An endpoints registration with a gatekeeper may have a limited life span. The gatekeeper specifies the registration duration for an endpoint by including a timeToLive field in the Registration Confirm (RCF) message. After the specified length of time, the registration is considered expired. The endpoint must periodically send a Registration Request (RRQ) having the keepAlive bit set prior to the expiration time. Such a message may include a minimum amount of information as described in H.225.0 and is known as a lightweight RRQ.

In the exhibit above, we can see the keepAlive bit is set to TRUE -> this is a lightweight RRQ.