Exam Essentials | Network+ Study Guide

Be able to specify the main features—including speed, access method, topology, and media—of various network technologies, such as 802 standards and FDDI. You should be able to differentiate between the various technologies when studying for the exam. Refer to Table 2.2 for help.

Be able to identify a MAC address. A MAC address on a network is a 12-digit hexadecimal number in the format xx:xx:xx:xx:xx:xx where x is a number from 0 to 9 or a letter from A through F.

Be able to identify the seven layers of the OSI model and describe their functions. The seven layers of the OSI model (from the bottom to top or Layer 1 to Layer 7) and their functions are:

Physical layer, which is responsible for placing data on the network in the form of electrical signals
Data Link layer, which is responsible for dividing datagrams into packets as well as physical addressing
Network layer, which is responsible for network addressing and routing
Transport layer, which is responsible for reliable end-to-end data delivery and flow control
Session layer, which is responsible for establishing and maintaining a session, or dialog
Presentation layer, which is responsible for the “look” of the data, including encryption/decryption and character-set translation
Application layer, which is responsible for providing network services

Know how to differentiate between the IP, IPX, NetBEUI, and AppleTalk protocols when it comes to routing, addressing schemes, interoperability, and naming conventions. TCP/IP uses RIP or OSPF for routing protocols, uses a dotted decimal notation (four sets of numbers, each from 0 to 255) for the addressing, is completely interoperable, and uses DNS for host naming.

IPX, on the other hand, uses IPX RIP and NLSP for routing information, uses a unique 20-digit address (incorporating the MAC address) for the station address, interoperates with several different operating systems (but not as many as TCP/IP), and uses NDS for host naming.

NetBEUI isn’t as flexible or has as many features, but does offer performance on a LAN segment. Addressing and naming are completely automatic (naming does require a user to enter a station name).

Finally, AppleTalk does have routing protocols (RTMP), and uses an automatic addressing scheme. It requires only that the user name the computer when enabling AppleTalk. It is by far the simplest protocol, but has the lowest performance and the least interoperability.

Be able to explain the issues that must be considered when multiple protocols are running at the same time. When running multiple protocols, not only are you using more memory on a computer, but you’re adding a level of complexity to the network that is multiplied by the number of stations that you add. It is better to run the fewest protocols possible. Some issues you will see include running out of memory, program confusion, stations unable to communicate (each is running a different protocol), and network congestion.

Identify the OSI layers at which hubs, switches, bridges, routers, and network interface cards operate. Hubs operate at the Physical layer for the most part. Switches can operate at many different layers (up to Layer 5), but the lowest common denominator for all network switches is OSI Layer 2 (Data Link layer). Bridges are relatively simple devices and operate primarily at the Data Link layer. Routers are more complex devices, but because all they do is route packets, they operate at Layer 3 (Network layer). Finally, network interface cards (NICs) operate at the Physical and Data Link layers.