B. The advantage of a Unix server is that it is very flexible in regard to the type of clients that can be used on it. The biggest disadvantage is that Unix servers are primarily configured and controlled using the command line.

A, C, D. The most basic components required for connectivity in a network are a common client, a common protocol, and network media. Many dissimilar operating systems can be connected through a network. Networks only require routers if they are intended to connect to other networks or to the Internet.

D. A tone locator is used to receive the signal produced by a tone generator. The ability to receive the signal proves the continuity of the wires within the cable. Neither a media tester nor a punch-down tool is used for this purpose.

C. SSH is a remote administration and remote control protocol similar to Telnet. The biggest difference between SSH and Telnet is that SSH encrypts a user's credentials while the user is authenticating and then maintains a secure environment throughout the session. This results in a much more secure method of remote administration. SSL is used to secure communication on the Internet for banking and e-commerce. MS-CHAP is a remote access authentication protocol used only by Microsoft clients.

D. The only Microsoft Windows client operating system that includes a built-in firewall is Windows XP. The builtin firewall is referred to as the Internet Connection Firewall (ICF). It controls traffic going into, but not out of, the computer.

A, C. The main benefits of using a proxy service are improved performance, improved control, and reporting. A proxy service does not provide more available RAM. A proxy service does not provide a user with access to any sites to which he would not otherwise have access.

A, D. Virtual local area networks (VLANs) are logical subnets that are created using a switch, not a hub. VLANs cannot communicate with other VLANs without using a router. VLANs provide simplified administration, through greater flexibility in network design.

B, D. Extranets are formed when an organization decides to give employees of another organization restricted access to its network. Extranets provide a value-added resource for a vendor or partner of a company. Extranets do not increase security in a network and in fact might actually pose a security risk unless they are configured properly. Extranets require additional security measures in regard to authentication and authorization.

A, C. Antivirus software is designed to keep viruses from damaging or computers and data, but it requires regular updates of virus definitions in order to remain effective. Antivirus software is designed for clients as well as servers. It should be installed on all of the computers in an organization. Not only is it affordable, but actually an organization can't afford to do without it.

B. RAID 1 can be used to provide fault-tolerant storage for the drive that contains the system files on a server. RAID 0 does not provide fault tolerance. RAID 5 cannot be used on the drive that contains the system files.

C. The IBM Token Ring network uses multistation access units (MSAUs) instead of normal hubs. The MSAUs contain the ring; therefore the IBM Token Ring network is a physical star and a logical ring.

A, C. The 802.11b wireless protocol is capable of communicating at a maximum of 11 Mbps. It can also communicate at a considerably lower speed depending on the device and the conditions of the environment. It cannot communicate faster than 11Mbps.

B, D. The and 802.11b and 802.11g network uses the 2.4GHz radio band. A 2.4GHz wireless phone, or a Bluetooth device (which also uses the 2.4GHz radio band) can interfere with this type of network. An FM radio and a 900MHz wireless phone are not likely to interfere with this type of network.

C, D. In a network using twisted-pair wire, a crossover cable should be used to connect similar devices. In a network using coaxial cable, the coaxial cable can be used as long as it is terminated on both ends. You should not use a straight-through cable or a rollover cable to connect similar network devices.

A, B. A firewall is a hardware device and/or software program that filters packets into and out of a network. Firewalls can filter packets by application, port number, IP address, and more. Firewalls do not assign temporary IP addresses or resolve hostnames to IP addresses.