An information bank has been established to store contacts, phone numbers and other records. A UNIX
application needs to connect to the index server using port 389. Which of the following authentication
services should be used on this port by default?

A.
RADIUS

B.
Kerberos

C.
TACACS+

D.
LDAP

Explanation:
LDAP makes use of port 389.
Incorrect Answers:
A: RADIUS makes use of various UDP ports.
B: Kerberos makes use of port 88.
C: TACACS makes use of TCP port 49 by default.

http://en.wikipedia.org/wiki/List_of_TCP_and_UDP_port_numbers