To securely use dynamic DNS updates, the use of TSIG is recommended. Which TWO statements about TSIG are true?

To securely use dynamic DNS updates, the use of TSIG is recommended. Which TWO statements about TSIG are true?

A.
TSIG is used for zone data encryption

B.
TSIG is a signal to start a zone update

C.
TSIG is used in zone files

D.
TSIG is used only in server configuration

E.
Servers using TSIG must be in sync (time zone!)