A new virtual server was created for the marketing department. The server was installed on an existing host machine. Users in the marketing department report
that they are unable to connect to the server. Technicians verify that the server has an IP address in the same VLAN as the marketing department users. Which of
the following is the MOST likely reason the users are unable to connect to the server?

A.
The new virtual server’s MAC address was not added to the ACL on the switch

B.
The new virtual server’s MAC address triggered a port security violation on the switch

C.
The new virtual server’s MAC address triggered an implicit deny in the switch

D.
The new virtual server’s MAC address was not added to the firewall rules on the switch

Explanation:
Configuring the switch to allow only traffic from computers based upon their physical address is known as MAC filtering. The physical address is known as the MAC
address. Every network adapter has a unique MAC address hardcoded into the adapter. You can configure the ports of a switch to allow connections from
computers with specific MAC addresses only and block all other MAC addresses.
In computer networking, MAC Filtering (or GUI filtering, or layer 2 address filtering) refers to a security access control method whereby the 48-bit address assigned
to each network card is used to determine access to the network.
MAC addresses are uniquely assigned to each card, so using MAC filtering on a network permits and denies network access to specific devices through the use of
blacklists and whitelists. While the restriction of network access through the use of lists is straightforward, an individual person is not identified by a MAC address,
rather a device only, so an authorized person will need to have a whitelist entry for each device that he or she would use to access the network.
Incorrect Answers:
B: The new virtual server’s MAC address triggering a port security violation on the switch may happen if the MAC address was not added to the ACL on the switch.
However, the port security violation is not the actual cause of the users being unable to connect to the server. The MAC address not being added to the ACL on the
switch is what would prevent the users connecting to the server. Therefore this answer is incorrect.
C: The new virtual server’s MAC address triggering an implicit deny in the switch would happen if the MAC address met a condition that caused the deny. This is
unlikely. The MAC address not being added to the ACL on the switch to allow access if more likely. Therefore this answer is incorrect.
D: Dedicated network switches don’t tend to have firewalls. A typical home wireless router may function as a switch and a firewall. However, even in this case, the
firewall typically wouldn’t prevent communications between devices connected to the switch. This answer is very unlikely and is therefore incorrect.

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