To comprehend working of the Internet, it essential to understand its three mains parts:
- The fundamental transport protocol – how data moves around the Internet
- Domain names and domain name resolution – how things are termed or referenced on the Internet
- Servers, routers, clients – the hardware of the Internet
The fundamental means of moving data in the online world is controlled by a protocol called TCP/IP, or transmission control protocol/Internet protocol. TCP/IP is also used on private networks, such as the office local area network (LAN) or home network. As the name suggests, TCP/IP is the combination of TCP and IP protocols working in tandem.
Under TCP/IP, a file is broken into smaller parts known as 'packets' by the file server. Each packet is assigned an IP (Internet protocol) address of the computer where it needs to reach. As the packet moves through the global network it is 'switched' by a number of servers and routers along the way toward its final destination – the requesting computer or 'client' computer.
The IP address tells those servers which way to direct the packet. Each time the packet is directed a "wrapper" is also added to the packet – this way, a professional can check as to how many computers were involved and which computer handled the file while it was in transit. This can be checked with the command "tracert" at the command line of your computer. Tracert stands for "trace route".
The packets do not essentially travel together on the Internet. Packets from the same file may travel via different paths through several different servers, but they move towards the same destination – the unique IP address where they are supposed to reach.
Packaging technology makes it possible to use limited bandwidth most efficiently. This implies that parts of a file can be shared across a number of phone lines instead of having to find one phone line to put a large file into. It is also complex to break the network, as the data will be routed around the trouble spot. In this respect TCP/IP may be compared to a group of 10 hitch seekers (the packets) who can not get a lift all together, but easily get lifts if they break up and choose to go by different cars and probably also by different roads, agreeing to finally meet up together at a particular point.
Domain names and domain name resolution
Computers and other network devices on the Internet use an IP address to route a request to the site that we try to reach. This is similar to dialing a phone number to connect to the person who we may be trying to call. Thanks to domain name system or DNS there is no need to keep an address book of IP addresses. Instead, we can just connect through a domain name server, also called a DNS server or name server that manages a massive database to map domain names to IP addresses.
A domain name is typically the business' or an organization’s name on the Internet. It is a subset of the email address after the "@" sign or part of the web address after the “www”.
You may be trying to access a website or send an e-mail, the computer uses a DNS server to look up the domain name that you are trying to access. The actual term for the process is DNS name resolution – the DNS server resolves the domain name to the IP address. For example, when you enter "https://www.computeruser.com/" in your browser, part of the network connection includes resolving the domain name "computeruser.com" into the numeric IP address for computeruser web servers.
Once a domain name is registered, it is "delegated" to a server. Delegation implies pointing the domain name at the server. That server then answers file transfer protocol requests, receives email and serves web pages for that domain.
To delegate a domain name, a website owner needs to know the name servers of the company that will maintain his/her web site and email. This company is known as the "host".
The host maintains a DNS server, or "domain name server". This is typically a software server that runs continuously. It answers calls for the domain (delegated to that server), directs requests and inbound data to different facilities of the host’s server. DNS server may be thought of as a table that helps the server route traffic to different IP addresses.
Domain names are a letter equivalent of numeric IP addresses and exist because IP addresses cannot be recalled easily. Domain name system is designed to define
- which server will answer requests for which domain name i.e. which server is "authoritative" for which domain name
- which IP addresses "resolve" to which domain names
Hardware for the Internet
Internet hardware comprises servers, routers and clients.
Servers are powerful computers that run round the clock. They need to work seamlessly and any failure in their working can result in total loss of Internet connection. Servers are specially constructed with redundant hard drives, extra cooling and are generally "rack optimized" – this implies that they are very flat and deep and are intended to slip into a rack of 32 similar machines.
Routers are hardware that pass data onwards to its destination IP.
Client machine is the end user that requests a web page or downloads the email. The client machine uses a browser and an email client to perform these functions. The server waits for a request from a client, then grabs the requested data and serves it back.
Physical connections between servers, routers and clients vary. Between a computer and telephone exchange, there is a twisted pair copper wire for data transfer, between exchange and the ISP, there is fiber optic cable. Further, between ISP and ISP, there are TI carriers – the main routes of the Internet.
So, it is the working of the transport protocol and domain name system on the Internet hardware that makes accessing websites, sending of emails and messages and posting of content possible. Any error in these on in the network can result in a slow connection or disruption of service!
About the Author:Frank Johnson is a regular editorial contributor on technology products and services that help small to mid size businesses. To know more about Internet and its working, you may interact with him here