• TCP/IP - TCP/IP is the most commonly used protocol today. It is the one used on the internet and most other networks. It will be covered in the next sections.
• IPX/SPX - These protocols were developed by Novell and are/were used with Novell Netware. IPX is the fastest routable protocol and is not connection oriented. IPX addresses are up to 8 characters in hexadecimal format. SPX is connection oriented.
• NWLink - Microsoft's implementation of the Novell NetWare IPX/SPX protocol for Windows NT Server and Workstation. Not very common anymore.
• NetBeui - Stands for "NetBIOS Extended User Interface". It was the standard protocol used by older Microsoft operating systems. It is NetBEUI that allowed the "shares' between machines. In reference to the NetBIOS distinction, NetBIOS is the applications programming interface and NetBEUI is the transport protocol. NetBEUI is a non-routable protocol meaning it will not allow communication through a router. This protocol is not used much anymore.

• TCP - TCP breaks data into manageable packets and tracks information such as source and destination of packets. It is able to reroute packets and is responsible for guaranteed delivery of the data.
• IP - This is a connectionless protocol, which means that a session is not created before sending data. IP is responsible for addressing and routing of packets between computers. It does not guarantee delivery and does not give acknowledgement of packets that are lost or sent out of order as this is the responsibility of higher layer protocols such as TCP.
• ICMP - Internet Control Message Protocol enables systems on a TCP/IP network to share status and error information such as with the use of PING and TRACERT utilities.
• SMTP - Used to reliably send and receive mail over the Internet.
• FTP - File transfer protocol is used for transferring files between remote systems. Must resolve host name to IP address to establish communication. It is connection oriented (i.e. verifies that packets reach destination).
• ARP - provides IP-address to MAC address resolution for IP packets. A MAC address is your computer's unique hardware number and appears in the form 00-A0-F1-27-64-E1 (for example). Each computer stores an ARP cache of other computers ARP-IP combinations.
• POP3 - Post Office Protocol. A POP3 mail server holds mail until the workstation is ready to receive it.
• TELNET - Provides a virtual terminal or remote login across the network that is connection-based. The remote server must be running a Telnet service for clients to connect.
• HTTP - The Hypertext Transfer Protocol is the set of rules for exchanging files (text, graphic images, sound, video, and other multimedia files) on the World Wide Web. It is the protocol controlling the transfer and addressing of HTTP requests and responses.

• 21 FTP
• 23 TELNET
• 25 SMTP
• 80 HTTP
• 110 POP3

TCP/IP Addressing:
Every IP address can be broken down into 2 parts, the Network ID(netid) and the Host ID(hostid). All hosts on the same network must have the same netid. Each of these hosts must have a hostid that is unique in relation to the netid. IP addresses are divided into 4 octets with each having a maximum value of 255. We view IP addresses in decimal notation such as 124.35.62.181, but it is actually utilized as binary data.

IP addresses are divided into 3 classes as shown below: