By Mark Tilden

10BaseT, 100BaseT, 1000BaseT: A type of Ethernet network that is based on twisted-pair cable (as compared with coaxial cable, such as TV cable) and connects with plugs and jacks that are similar to a phone jack. The first number refers to the speed of the network. 10BaseT transfers data at 10Mbps (10 million bits per second). Similarly, 100BaseT transfers data at 100Mbps, and 1000BaseT transfers data at 1Gbps (1 billion bits per second).
Bridge: A general term that refers to a device that connects two networks. A wireless bridge, for example, might connect one group of computers in one building (or on your boat) to another group of computers in your home or another building. The wireless bridge connects the two networks and makes them function as one larger network.
Cat 5/Cat 5e/Cat 6: Category 5, Category 5e (“enhanced”), or Category 6 cable as specified by the EIA/TIA-568 standards. These are types of unshielded twisted-pair (UTP) cables that are suitable for building an Ethernet network. The EIA/TIA standard does not specify shielded cable, but shielded twisted-pair (STP) cable will work and offers better immunity to the high levels of electrical noise often found on modern trawlers.
Client: Users’ computers that are connected in a server-based network are typically called “clients” because they use the services offered by a “server.” (See “server” and “peer-to-peer network.”)
DHCP: Dynamic Host Configuration Protocol is a means for automatically assigning important network parameters, including an IP address, to a computer when it connects to the network. Many devices can operate as a DHCP “server,” which is responsible for controlling the process of automatic configuration of devices plugged in (or wirelessly connected) to the network. Most routers have DHCP servers built in.
File server: A computer dedicated to providing shared storage for any number of other computers connected to the network.
Firewall: A device (usually a router or specially equipped computer) or software that protects a network from electronic intrusion via a broader public network such as the Internet. The firewall prevents another person on the Internet, for example, from accessing files that are meant to be shared only by other users on a local network and are not intended to be accessible from the public Internet.
Hub: A device that is at the center of a “star” configuration in an Ethernet network. The hub simply echoes every message it receives on any of its ports to all the other ports, regardless of the actual destination address of the message.
IP address: The unique address that is used to identify a computer on a TCP/IP network. IP addresses are in the form: xxx.xxx.xxx.xxx (where xxx is a number between 0 and 255). Some IP addresses are “public” IP addresses in that they are assigned to computers or routers that connect directly to the Internet. “Private” IP addresses are reserved for computers or devices that are on a private network, separated from the Internet by a router.
LAN: Local area network. This is the private part of your network that is usually separated from the Internet by a router.
MAC address: Media Access Control address. Sometimes referred to as “physical address.” Every Ethernet device has a unique MAC address that is in the form of 12 hexadecimal digits (0-9 and A-F). MAC addresses are typically written as six pairs of two hexadecimal digits separated by colons or dashes. A typical MAC address looks like this: 00-11-11-71-82-B4.
NAS: Network-attached storage. A disc drive connected directly to a network with appropriate software to allow computers on the network to access and use the storage as if it were part of their own built-in disc space. NAS devices are a great low-cost and easy-to-administer alternative to a dedicated file server computer.
Peer-to-peer network: A network of computers without a server. All the computers on the network are “peers” in the sense that no individual computer has special control over the network.
Protocol: In networking terms, a “protocol” is a set of communication rules. It’s an agreement about how two computers will exchange messages.
Router: A device that connects a group of computers in a local network to a larger network. In most small home or onboard networks, the router is the connected between all the local computers and the Internet. The router may also serve as a “firewall” (see “firewall”).
Server: A general term for a computer that provides services to “client” computers on the network (see “client”). A server may provide a single service, such as validation of user logins, or it may provide many services, including shared file storage, printing, user logins, etc. A network can have any number of servers, as long as the services they provide do not conflict.
SSID/ESSID: Service Set Identifier/Extended Service Set Identifier. This is the electronic name of a wireless network. When you set up a wireless network, you choose the SSID for your network.
Switch: A switch is a more advanced type of hub. Instead of sending every message it receives on one of its ports to all the other ports, it intelligently routes the message only to the port that is connected to the device identified by the destination address. A switch handles network traffic more efficiently because it doesn’t send unnecessary traffic to all the devices on the network.
TCP/IP: Transmission Control Protocol/Internet Protocol. TCP/IP is the protocol that defines how computers exchange messages on the Internet and on your private network, if it uses TCP/IP. TCP and IP are actually separate parts of a set of protocols used on the network, but they usually work together.
WAN: Wide area network. A general term for a network the connects a larger, often public, group of computers. The Internet is considered a WAN. Most routers have a WAN port that is intended to be connected to the Internet via a DSL or cable modem or wireless access point, and one or more LAN ports that are intended to be connected to a local network.
WEP: Wired Equivalent Privacy. This is an encryption algorithm that is designed to prevent electronic intruders from “reading” your private messages sent over a wireless network. WEP is widely considered to be relatively easy to break, so more secure encryption techniques like WPA were created.
WPA: Wireless Protected Access. This is a more sophisticated encryption algorithm that is harder to break than WEP. It is less commonly used that WEP but is available in most wireless devices sold in the last two years.