TCP/IP - TCP/IP (Transmission Control Protocol/Internet Protocol) is the basic communication language or protocol of the Internet or a network. TCP/IP is a two-layer model with the higher layer (Transmission Control Protocol) managing the assembling of a message or file into smaller packets that are transmitted over the Internet and received by a TCP layer that reassembles the packets into the original message. The lower layer (Internet Protocol) handles the address part of each packet so that it gets to the right destination. Each gateway computer on the network checks this address to see where to forward the message. Even though some packets from the same message are routed differently than others, they will be reassembled at the destination.
IPX/SPX - Short for Sequenced Packet Exchange, a transport layer protocol used commonly in Novell Netware networks. The SPX layer sits on top of the IPX layer and provides connection-oriented services between two nodes on the network. SPX is used primarily by client/server applications. Whereas the IPX protocol is similar to IP, SPX is similar to TCP. Together, therefore, IPX/SPX provides connection services similar to TCP/IP.
Netbios - NetBIOS (Network Basic Input/Output System) is a program that allows applications on different computers to communicate within a local area network (LAN). NetBIOS frees the application from having to understand the details of the network, including error recovery (in session mode). A NetBIOS request is provided in the form of a Network Control Block (NCB) which, among other things, specifies a message location and the name of a destination.
UDP - User Datagram Protocol is a connectionless protocol that, like TCP, runs on top of IP networks. Unlike TCP/IP, UDP/IP provides very few error recovery services, offering instead a direct way to send and receive datagrams over an IP network. It is used primarily for broadcasting messages over a network.
DHCP - Dynamic Host Configuration Protocol, a protocol for assigning dynamic IP addresses to devices on a network. With dynamic addressing, a device can have a different IP address every time it connects to the network. In some systems, the device\'s IP address can even change while it is still connected. DHCP also supports a mix of static and dynamic IP addresses.
DNS - Domain Name System (or Service or Server), an Internet service that translates domain names into IP addresses. Because domain names are alphabetic, they are easier to remember.
DNS ROOT SERVERS - One of several domain name system (DNS) servers on the Internet that contain the IP addresses of the top level domain (TLD) registry organizations that maintain the global domains (.com, .net, .gov, etc.) and country code domains (.uk, .ca, .fr, etc.). The first point of entry for resolving a domain name, there are currently 34 root servers throughout the world operated by government agencies and private organizations, all of which contain the same data.
WINS - Windows Internet Naming Service, a system that determines the IP address associated with a particular network computer. This is called name resolution. WINS supports network client and server computers running Windows and can provide name resolution for other computers with special arrangements. WINS uses a distributed database that is automatically updated with the names of computers currently available and the IP address assigned to each one.
127.0.0.1 - Localhost or default loopback.
Non-Routable IP Addresses - IP addresses are either "routable" or "non-routable". Routable addresses can be used to route on the Internet and Non-Routable addresses cannot be used to route on the Internet. Non-routable IP addresses are usually used behind firewalls. There are only 3 valid non-routable ranges:
IP of 1 - 254 with 255 being broadcast.
Subnet - A portion of a network that shares a common address component. On TCP/IP networks, subnets are defined as all devices whose IP addresses have the same prefix. For example, all devices with IP addresses that start with 192.168.1 would be part of the same subnet. Dividing a network into subnets is useful for both security and performance reasons.
Subnet Mask - A mask used to determine what subnet an IP address belongs to. An IP address has two components, the network address and the host address. Subnetting enables the network administrator to further divide the host part of the address into two or more subnets.
Network Gateway - A node on a network that serves as an entrance to another network. In enterprises, the gateway is the computer that routes the traffic from a workstation to the outside network that is serving the Web pages. In homes, the gateway is the ISP that connects the user to the internet. In enterprises, the gateway node often acts as a proxy server and a firewall. The gateway is also associated with both a router, which use headers and forwarding tables to determine where packets are sent, and a switch, which provides the actual path for the packet in and out of the gateway.
Half and Full Duplex - Refers to the transmission of data in two directions simultaneously. For example, a telephone is a full-duplex device because both parties can talk at once. In contrast, a walkie-talkie is a half-duplex device because only one party can transmit at a time.