Why would a network administrator configure port security on a switch?

A.
to block unauthorized access to the switch management interfaces over common TCP ports

B.
to limit the number of Layer 2 broadcasts on a particular switch port

C.
to prevent unauthorized Telnet access to a switch port

D.
to protect the IP and MAC address of the switch and associated ports

E.
to prevent unauthorized hosts from accessing the LAN

Explanation:

You can use the port security feature to restrict input to an interface by limiting and identifying
MAC addresses of the stations allowed to access the port. When you assign secure MAC
addresses to a secure port, the port does not forward packets with source addresses outside the
group of defined addresses. If you limit the number of secure MAC addresses to one and assign a
single secure MAC address, the workstation attached to that port is assured the full bandwidth of
the port.
If a port is configured as a secure port and the maximum number of secure MAC addresses is
reached, when the MAC address of a station attempting to access the port is different from any of
the identified secure MAC addresses, a security violation occurs. Also, if a station with a secure
MAC address configured or learned on one secure port attempts to access another secure port, a
violation is flagged.
Reference:
http://www.cisco.com/en/US/products/hw/switches/ps628/products_configuration_guide_chapter0
9186a00800d6a38.html#86378