Basics about Networking (CCNA) Part 6

What is IP Address?

Internet Protocol Address (or IP Address) is an unique address that computing devices use to identify itself and communicate with other devices in the Internet Protocol network. Any device connected to the IP network must have an unique IP address within its network. An IP address is analogous to a street address or telephone number in that it is used to uniquely identify a network device to deliver mail message, or call ("view") a website.
A unique string of numbers separated by periods that identifies each computer attached to the Internet. It also usually has a version.

Why IP is required?

In order to identify a computer in a network of devices IP address is must. Your name is your identification when you are in a crowd. Likewise an IP address is the identification factor used to identify an individual device in a network. Every intelligent device has its own ip address. By typing a web address in browser, you are literally calling the ip address of another computer/server. If you want to see your ip addresses go to command prompt and type 'ipconfig' without quotes. In order to see your network adapter address also, type ipconfig/all.

Try this also type tracert<space>web address

e.g tracert yahoo.com

you can see the computer ip address assigned with yahoo.

IP versions?

Two versions of the Internet Protocol (IP) are in use:

IP Version 4 and IP Version 6

Each version defines an IP address differently. Because of its prevalence, the generic term IP address typically still refers to the addresses defined by IPv4. The gap in version sequence between IPv4 and IPv6 resulted from the assignment of number 5 to the experimental Internet Stream Protocol in 1979, which however was never referred to as IPv5.

IPv4 addresses.

In IPv4 an address consists of 32 bits which limits the address space to 4294967296 (2³²) possible unique addresses. IPv4 reserves some addresses for special purposes such as private networks (~18 million addresses) or multicast addresses (~270 million addresses)IPv4 addresses are canonically represented in dot-decimal notation, which consists of four decimal numbers, each ranging from 0 to 255, separated by dots, e.g., 192.168.254.1. Each part represents a group of 8 bits (octet) of the address. In some cases of technical writing, IPv4 addresses may be presented in various hexadecimal, octal, or binary representations.

IPV6 addresses.

The rapid exhaustion of IPv4 address space, despite conservation techniques, prompted the Internet Engineering Task Force (IETF) to explore new technologies to expand the addressing capability in the Internet. The permanent solution was deemed to be a redesign of the Internet Protocol itself. This next generation of the Internet Protocol, intended to replace IPv4 on the Internet, was eventually named Internet Protocol Version 6 (IPv6) in 1995.The address size was increased from 32 to 128 bits or 16 octets. This, even with a generous assignment of network blocks, is deemed sufficient for the foreseeable future. Mathematically, the new address space provides the potential for a maximum of 2¹²⁸, or about 3.403×10³⁸ addresses.

IP sub networks?

IP networks may be divided into sub networks in both IPv4 and IPv6. For this purpose, an IP address is logically recognized as consisting of two parts: the network prefix and the host identifier, or interface identifier (IPv6). The subnet mask or the CIDR prefix determines how the IP address is divided into network and host parts.

The term subnet mask is only used within IPv4. Both IP versions however use the CIDR concept and notation. In this, the IP address is followed by a slash and the number (in decimal) of bits used for the network part, also called the routing prefix. For example, an IPv4 address and its subnet mask may be 192.168.2.1 and 255.255.255.0, respectively. The CIDR notation for the same IP address and subnet is 192.168.2.1/24, because the first 24 bits of the IP address indicate the network and subnet.

Types of IP Address and its requirements?

IP addresses are basically of two types:

1) Static IP address

2) Shared IP address

An IP Address is a 32-bit number that identifies a computer on the Internet. Every web site on the internet is found not by its domain name but by its IP address. When someone types the address: www.xyz.com it is translated into an IP address and then the computer is directed to that IP address which is the web site. Now every single website has an IP address specifically allocated to it. If every site assigned a separate IP address then there could be a problem with running out of IP addresses so a lot of the sites on the server use a single IP address for multiple sites. 

Thus, using more than one site on an IP address is called a Shared IP address. If a site has its own IP address, and shares with no one else, it is called a Static IP address. You can always access a site which has a static IP address by using its IP address alone, but you cannot access a site using a shared IP address by typing in the IP address alone because when you type in a shared IP address you arrive at the server but the server does not know which site you are looking for as you have not told it which domain name you want. 

What's the Difference Between a Static and a Dynamic IP Address?

The IP address from your ISP is assigned one of two ways:

Set to an IP address which is unchanged for months or years at a time. This is a static IP address. Set to an IP which is only good for a limited time, and which is changed according to the policy set by your ISP's DHCP server. This is a dynamic IP address. Because a static IP can be relied on for an indefinite period, some networking software requires a static IP. ISPs usually charge extra for static IPs. Your ISP may not be willing to give their customers static IP addresses at all. Dynamic IP is used in large networks where computers are frequently reconfigured, or where a limited number of IP address are available to share between many computers.

Requirement of static IP address:

1) The main reason to have a static IP address for your site is that, you can use SSL (Socket Secure Layer) encryption on a static IP address only. In order to transmit sensitive data over the internet, it must be encrypted to prevent someone from intercepting the information.

2) In case if the site needed the anonymous ftp access (anyone can download files of the site), the site needs to have a static IP address.

Other than these two reasons there is no need for a site to have its own IP address.