You may know websites (such as google.com) by their domain names, but IP numbers are associated with the sites behind the scenes.
Think of an IP number like a street address. A street address uniquely identifies a building or residence. Similarly, an IP number uniquely identifies the web server the domain name and website is on.
The term “IP number” is also known as an “IP address”.
Domain Name to IP Number Conversion
When you use a browser to surf to a name, it must first resolve and obtain the IP number for the domain name you request. A Domain Name Server (DNS), a computer with lookup tables for domain names and their assigned IP numbers, translates it. The DNS table returns the IP number from the request, then the corresponding web server (where the IP number is assigned) grabs your request, translates the IP number back to the domain name, and displays the web site to you. The name-to-IP number conversion is quick and transparent. However, technicians who monitor traffic across the Internet between web servers and other devices see IP numbers, not domain names.
Technicians See IP Addresses
Technicians see IP addresses, not domain names, because they see traffic in the communication path after a request has been converted from a domain name into its IP address. For example, when you browse to a name, a technician sees your IP address making a request to the webserver. The technician doesn’t know who is making the request. They know the IP address assigned to you at the time of your request.
The same thing happens when one website requests another website. Again, the technician can’t see who is making the request. They know the IP address assigned to the requesting website. If the web site is on a shared IP address, hundreds of websites could be sharing that address. Knowing which one is making the request requires contacting the hosting company assigned to the IP address.
Technicians Monitor Traffic by IP Numbers
One part of a technician’s job is to monitor requests to the web servers they manage and identify and block those abusing the system.
Here’s an everyday example. You own a business and have a website. Your hosting provider puts your website on a shared IP address with other websites on the server. An owner of another web site, sharing the same IP address as you, abuses some policy whether knowingly or unknowingly (as in the case of a runaway script) in such a way that it adversely affects other web sites, web servers, or other devices on the Internet. The only immediate recourse that a technician on the receiving end of the abuse has is to block the IP address of the abuser. If your website is on a shared IP address with the abuser, your website is blocked too. However, if your web site is on a dedicated IP address, it is not blocked, in this particular case, and not affected by what others do.
IP numbers not only help locate websites on the Internet, but they also help technicians track traffic.
Parts of this article are copyright WAASI, Inc., and are used with permission.