IP - Internet Protocol

The Network Layer protocol for TCP/IP is the Internet Protocol (IP). It uses IP addresses and the subnet mask to determine whether the packet is on the local or a remote network. If it is on the remote network, the packet is forwarded to the default gateway which is a router that links to another network. This page discusses IP version 4 or IP4 which is the most widely used version. IPv6 is now being introduced and is not as common at the desktop. Expect to hear more about IPv6 in the future.

IP address bits

IP keeps track of the number of transverses through each router that the packet goes through to reach its destination. Each transverse is called a hop. If the hop count exceeds 255 hops, the packet is removed and the destination considered unreachable. IP's name for the hop count is called Time To Live (TTL).

Hop Count is one transverse through a router.

IP Addresses

IP addresses consist of a 32 bit number and is represented by the dot-decimal format. for example: is an IP address. There are 4 decimal digits separated by three dots. Each digit is allowed the range of 0 to 255 which corresponds to 8 bits (one byte) of information.

IP address bits

A portion of an IP address represents the network address and the remaining portion the host address. For example: is the IP address of a PC. The network that the PC resided on is (Note: IP addresses that end in a 0 represent network addresses). The host address of the PC is (Note: the network portion of the IP address is represented by 0s). Each host on the network and Internet must have a unique IP address. Often the host portion will be referred to as just .10 pronounced "dot ten".

Network portion = 142.110.237 .10 = Host portion

The Internet Corporation for Assigned Names and Numbers (ICANN) coordinates the Domain Name System (DNS), Internet Protocol (IP) addresses, space allocation, protocol identifier assignment, generic (gTLD) and country code (ccTLD) Top-Level Domain name system management, and root server system management functions. These services were originally performed under U.S. Government contract by the Internet Assigned Numbers Authority (IANA) and other entities. ICANN now performs the IANA function.

2012 was when there were no more public IP addresses available.

You must apply to receive a public IP network address. Unfortunately, even though there are 4,294,967,296 possible unique addresses, there are no public IP addresses available anymore. They've all been assigned. You must "rent" IP addresses from your local Internet Service Provider (ISP). They usually own the rights to a block of IP addresses and will rent them out for a fee.

An alternative is to hide your network behind one public IP address using a technology called Network Address Translation (NAT). This mechanism has been a life saver for the Internet and it is incorporated into every broadband router.

The IP - Internet Protocol section is divided into the following sub sections:

IP Address Classes - There is a formal structure to the assignment of IP addresses. IP addresses are assigned by the Network Information Center (NIC) who is a central authority with the responsibility of assigning network addresses.

IP Address Masks - The network mask is used to determine which portion of the IP address is the network address and which is the host address.

Domain Names - IP addresses are difficult for humans to remember, they're great for PCs! Domain names were invented to make it easier to navigate the Internet.

IPv4 Header - The IPv4 packet is divided into fields of which make up the IP header. Here's the information on the IP header.

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Copyright July 2013 Eugene Blanchard