On which two ports does the RADIUS server maintain a database and listen for incoming authentication and accounting requests? (Choose two.)

A.
UDP 1900

B.
UDP port 1812

C.
TCP port 1812

D.
TCP port 1813

E.
UDP port 1813

Explanation:
RADIUS messages are sent as User Datagram Protocol (UDP) messages. UDP port 1812 is used for RADIUS authentication messages and UDP port
1813 is used for RADIUS accounting messages. Some network access servers might use UDP port 1645 for RADIUS authentication messages and UDP port 1646
for RADIUS accounting messages. By default, IAS supports receiving RADIUS messages destined to both sets of UDP ports.
https://technet.microsoft.com/en-in/library/cc781821(v=ws.10).aspx