Which statement below is correct regarding VLANs?

A.
A closed VLAN configuration is the least secure VLAN configuration.

B.
A VLAN is less secure when implemented in conjunction with private port switching.

C.
A VLAN is a network segmented physically, not logically.

D.
A VLAN restricts flooding to only those ports included in the VLAN.

Explanation:
A virtual local area network (VLAN) allows ports on the same or different switches to be grouped so
that traffic is confined to members of that group only, and restricts broadcast, unicast, and multicast
traffic. Answer “A VLAN is a network segmented physically, not logically” is incorrect, because a
VLAN is segmented logically, rather than physically. Answer “A VLAN is less secure when
implemented in conjunction with private port switching” is incorrect. When a VLAN is implemented
with private port, or single-user, switching, it provides fairly stringent security because broadcast
vulnerabilities are minimized. Answer “A closed VLAN configuration is the least secure VLAN
configuration” is incorrect, as a closed VLAN authenticates a user to an access control list on a
central authentication server, where they are assigned authorization parameters to determine their
level of network access. Sources: Catalyst 5000 Series Installation Guide (Cisco Systems) and Virtual
LANs by Mariana Smith (McGraw-Hill, 1998).