This is an introductory lesson for new SEOs that are not familiar with how the Internet and websites work. An SEO with a clear understanding of Internet technology will be able to understand a lot of technical processes that can help to diagnose SEO-related issues.
If you are ready, let's get started.
Technical definition of Internet
Let's start with the most basic lesson about Internet technology. The Internet is a network made up of a vast number of computers. The computers are either connected through the use of wire communications (through cables) or wireless communications (antennas).
Each of the computers on the Internet has been assigned a name with which to identify itself as "unique" in the network. This is called an IP address. An example of an IP address is 209.35.17.17. It is a numerical naming convention assigned to a network computer; this convention has existed ever since the birth of the Internet.
Using an IP address, you can determine the following information:
The computer's ISP (Internet service provider).
The computer's geographical location.
For example, you can use the following tool to determine your computer's IP address on the Internet: http://www.whatismyip.com/
Once you have your IP address, you can input the result into http://ip-lookup.net/. That tool will tell you your ISP hostname and your country of origin.
This is also the reason Google knows the exact geographical location of website servers, because of the server's IP address.
So what is an ISP? Their main job is to provide Internet connections to their subscribers. In return, subscribers make monthly payments to keep up their Internet connections.
To make things fast, especially when the ISP has a large number of Internet subscribers using connections at the same time, the ISP will implement its own DNS server. A DNS server actually works as a "cache," a temporary storage for "IP Address to Domain Name" system equivalents.
Since the Internet is a network of computers, each identified by its IP address, websites use an alias known as a "domain name" instead of an IP to make things easy for users to remember (it is easier to remember a word than a number).
A DNS server is used to convert these domain names into their IP address equivalents. So a DNS server holds the following information (for example):
Domain Name == IP Address seochat.com === 209.35.17.17 ibm.com === 129.42.38.1 apple.com === 17.251.200.70
The TCP/IP Internet protocol communicates with numbers and bits, and one piece of information used in the exchange of information is the IP address. So when a client browser visits a website, the ISP DNS server translates that domain name request into an IP address, for communication purposes.
The Hosting Name Server
Every website on the Internet is stored in a computer (like the computer you use at home). These computers are connected and identified on the Internet using an IP address (basic protocol discussed previously). Since websites use a domain name instead of an IP address, a "name server" holds the authoritative information pertaining to the website IP address (also known as the A-record) and the MX record (mail exchange record). Some records that can be found are the CNAME and others.
If you update a name server, the information about the website (its IP address , etc) will be "propagated" throughout the Internet, reaching as many DNS servers as possible at different Internet service providers. This process, called "DNS propagation," can take up to 48 hours to complete. This is why web developers often advise SEOs to start doing onsite work after a full/complete DNS update.
Once the DNS server has this information, it will be stored in its computer. If a client requests a certain website from the DNS server, the server will then look up its equivalent IP address to fetch content from the hosting server.
As of this point, we've covered the following (shown in communication diagrams):
The arrow pointing from the ISP DNS to the Website Name server and vice versa means that the DNS server fetches/updates information about the website's IP address, etc. The information is cached in the DNS server for a period of time.
This makes communication a little faster, as mentioned previously. If a web surfer sends a query about a domain, the DNS has this information cached and can quickly communicate further to retrieve the website's content (to be discussed in the next section).
The name server record is configured using your domain registrar control panel. Two of the most popular domain registrars are Go Daddy and Network Solutions. So if you register a domain name with a registrar and have a hosting account for your website, the hosting company will provide you with their name server information.
Examples of name servers are:
NS1.AGILITYHOSTER.COM
NS2.AGILITYHOSTER.COM
Once you have the name server information from your web hosting company, you will need to update that information with your domain registrar. If you switch to a different web hosting company, then you will also need to update the name server in your domain registrar control panel.
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