Internet Protocol

Internet protocol is a protocol or rule that determines how the data should be delivered over the internet. It defines the rule to identify a correct routing path and destination node. Each device adds its IP address and forwards it to the next device until the destination node is reached. In this process, the transport protocols of the OSI model or TCP model are used. The most common transport protocols are UDP and TCP.

What is IP Address? How its work?

An IP Address is 32 bits dotted decimal digits assign to the device to identify it on the internet. For example “192.168.12.12 “is the IP address of the device. When a user enters the human-readable domain names, domain name system (DNS) convert it into IP Address to locate the device.

Figure 1: IP Address

The Classes part is to identify the class. The network and the host number are used to identify the network in which device is present and the host number is used to identify the unique device respectively. There are two types of IP version that is IPv4 (32 bits) and IPv6 (128 bits).

Public and Private IP Address:

Private IP Address is used to communicate within the local network whereas public IP address is used to communicate outside the network. A public IP address is provided by Internet Service Provider (ISP) whereas anyone can use private IP address within the network.

The Range of Private IP Addresses are:

1. 10.0.0.0 - 10.255.255.255

2. 172.16.0.0 – 172.31.255.255

3. 192.168.0.0 – 192.168.255.255

The Range of Public IP Addresses are: Besides the private address, the rest is the public IP address.

The IP (commonly known as IPv4) datagram header format is shown in figure 2 below:

Figure 2: The IPv4 Datagram Address format

What is URL, DNS and IP Address?

Uniform Resource Locator (URL):

Uniform Resource Locator (URL) or informally know as web address, is the location of the specific website, pages or files present on the Internet. URL is defined in RFC 1738 by inventor of world wide web (www) Tim Berners Lee. URL is compose of different parts: a domain name, hostname and a file name with the extension. For example, the URL address ( https://www.blogger.com/index.html) contains a protocol (http) , a hostname ( www.blogger.com) and a file name (index.html). Figure 1 shows the URL parts.

Figure 1: Basic part of URL address.

The protocol is separated from URL through colon (:) and two forward slashes ( // ) whereas the domain name, directories , and files are separated by forward slashes( / ). A domain name is an identifier for a specific site using Top-level Doman (TLD) maintained by Internet Assigned Numbers Authority (IANA) at root Zone Database. Some of list of Top-Level Domain is given below:

Name	Entity	Purpose
.com	Commercial purpose	for profit business entities registered by individual or organization.
.org	Organization	used by non-profit organization
.net	Network	Used by distributed network of computers.
.int	Internet Assigned Numbers Authority	Strictly limited to organizations, offices, and program endorsed by treaty between countries.
.edu	Education	Limited to specific higher educational institutions.
.gov	General Services Administration	Limited to government organizations.

What characters are not allowed in a URL?

According to the RFC 1738 documentation, the URL string can only contains alphanumeric characters such as !$-_+*'(),characters. To add any other characters we have to encoded to the URL.

Parameters Associated with the URL:

The parameter associated in the URL is to performs additional functions and contains additional information to point to the search query made. Let consider an example to explain it properly.

https://www.blogger.com/u/1/blog/posts/739541721450841330?hl=en-GB

In the above URL, the question mark (?) separates the URL from all the parameters or variable. In example above hl is a variable name and the next part is value assign to that variable. In URL, no spaces are allowed however some time (+) is used to represent space. To represent the multiple variables, each variable can be separated with an ampersand (&) in the URL.

Where is the URL Located?

A URL is located in the address bar of the browser window of the computers. The display address on the address bar is the complete address of the current page located on the web server.

Note: An important thing to note is IP Address and URL is different.

An IP Address is a unique number that is assigned to each device on a network. On World Wide Web, each domain name has assigned a unique IP address. Then, Domain Name System (DNS) translates the domain name into an IP address that routers use to find the webserver. It means that it is easy to remember www.blogger.com than 201.124.12.12 (random example).

Domain Name System (DNS):

DNS is a hierarchical naming system for computers or devices to connect to the internet or a private network. It translates the more readable domain to the IP Address understood by a machine. It maintained the domain name hierarchy and provide translation services to the users using internet name servers and a communication protocol. A DNS name server is a server that stores the DNS records for a domain and responds to the queries made.

In laymen language, we can call DNS as a phone book of the internet which provides the service to the user in a friendly manner.

How does DNS work?
The DNS works involve converting a hostname (such as www.blogger.com) into a computer-friendly IP address (such as 201.124.12.12). An IP address is allocated to each device on the Internet, and that address is necessary to find the appropriate Internet device - like a street or colony address is used to find a particular house. When a user wants to load a webpage, a translation must occur between what a user types into their web browser (www.blogger.com) and the machine-friendly address necessary to locate the www.blogger.com webpage.

There are 4 DNS servers involved in loading a webpage:

DNS recursor - The DNS recursor is a server designed to receive queries from client machines through applications such as web browsers. Typically, the recursor is then responsible for making additional requests in order to satisfy the client’s DNS query.
Root nameserver - The root server is the first step in translating (resolving) human-readable hostnames into IP addresses. Typically, it serves as a reference to other more specific locations.
TLD nameserver- The top-level domain server (TLD) is the next step in the search for a specific IP address, and it hosts the last portion of a hostname (In blogger.com, the TLD server is “com”).
Authoritative nameserver - The authoritative nameserver is the last stop in the nameserver query. If the authoritative name server has access to the requested record, it will return the IP address for the requested hostname back to the DNS Recursor that made the initial request.