How is Kerberos a single sign-on technology?

A.
The user enters his credentials one time and obtains a TGT. The user uses the TGT each time he needs to communicate to a network resource.

B.
The user enters his credentials one time and obtains a TGS. The user uses the TGS each time he needs to communicate to a network resource.

C.
The AS keeps the users authentication information in memory to ensure that anauthenticated user does not need to continue to enter credentials.

D.
The TGS keeps the users authentication information in memory to ensure that anauthenticated user does not need to continue to enter credentials.

Explanation:
The user enters his credentials and obtains a TGT. The TGT has a time stamp that makes it valid for 8-10 hours, depending upon how the network administrator configured it. Each time the user needs to access a network resource, his Kerberos client sends the TGT to the TGS, which creates a second ticket. The second ticket is used by the user to authenticate to the network resource.