What You Need to
Know About IP Addresses
By John Buchanan (c) 2007

If you are new to the internet, often times things can seem quite overwhelming. People throw around terms like IP addresses, name servers, hosting, ftp, etc.

In this article we are going to cover IP Addresses. You'll learn exactly what they are and how they apply to search engine optimization (SEO).

IP Address stands for Internet Protocol Address and is currently made up of four "octets" or numbers separated by a period. Each octet can be a number from 0 to 255 .

Some examples of valid IP addresses are - 1.123.150.243, 35.35.36.10, 240.216.1.80

There is also a new standard for IP addresses that is slowly being launched called IPV6 (IP version 6). IPV6 numbers look quite different from our current IP addresses.

An example of an IPV6 IP address is -
2001:0db8:85a3:08d3:1319:8a2e:0370:7334

You will notice each is much longer with MANY more possible variations. The new IP system is designed to give us enough IP addresses so that we will not run out of unique IP addresses any time in the foreseeable future.

So why do we need IP addresses? Quite simply, an IP address is like your physical home address. It designates a specific computer that is connected to the internet. Every computer connected to the internet has an IP address. This is necessary for it to send and receive information.

When you type in a website name, for example mine, http://www.sesecrets.com, that name is translated into an IP address that is then used to "find" my site. In the current set of IP addresses, going from left to right, the first "octet" is the most broad, with each successive octet getting more and more granular or specific.

To explain that a bit better.

134 - is VERY broad
134.125 - is still quite broad, but getting more specific
134.125.244 - is getting more specific and probably refers to a specific web host
134.125.244.1 - is as specific as you can get and refers to a specific computer

You will often hear of different classes such as class A, class B and class C talked about when dealing with IP addresses. Below I've given some examples of what people are referring to when talking about classes.

Class A
134.XXX.XXX.XXX
240.XXX.XXX.XXX
22.XXX.XXX.XXX

Class B
134.254.XXX.XXX
36.36.XXX.XXX
36.37.XXX.XXX

Class C
254.210.135.XXX
36.36.1.XXX
36.36.2.XXX

It's often easiest to think of IP addresses as physical addresses, with the Class A octet being similar to country, Class B, being a city in that country, Class C being a street in that city, and the last octet being a specific house on that street.

So, by looking above you should be able to see that when someone talks about a Class A IP address they are referring to the first "octet" and when they say that two IP addresses are on different Class A subnets, it simply means the first set of numbers are different.

So for example

255.123.124.255
34.123.124.255

are on different Class A's. While the rest of the IP addresses are the same, because they are on different Class As, they are VERY far apart (remember, Class A is the most broad).

The same goes for Class B. Class B refers to the second octet of numbers. When someone says that two IP addresses are on different Class B's, it simply means that the the second octet's of each IP is different. The IPs may be on the same Class A or it may be different, but the second Octet of numbers is different. To better explain...look below.

255.123.124.255
255.34.124.255
34.34.124.255

In the above example, the first two IP addresses are on the same Class A, but different Class B's. The third IP address, has the same Class B number (34), but because the first Octet is different, it is also on a different Class B ( as with physical addresses, two countries can have the same city names, but they are still different cities).

For class C we are looking at the third octet.

255.123.124.255
255.123.34.255
34.42.124.255

Again, the first two above are on different Class C's, while the third has the same class C number as the first, but it's first and second octets are different, so it's also on a different Class C.

I hope the above makes sense to you. I've tried to give plenty of examples to make it clear no matter what your tech background is.

The good news is, that you hardly ever have to mess with IP addresses. When you get a web hosting account for your domain name, your host will assign your domain name and IP address. You often don't even HAVE to know it. Generally your host will set all this up for you without you having to understand any of it. From that point on, when someone types in your domain name, that name will then be converted to your assigned IP address and voila...your visitor winds up at your site.

About The Author

John Buchanan is a veteran search engine optimization specialist with over 9 years experience. For more information, visit his site at SESecrets.com or his newest site SEOVideoanalysis.com where he will provide you with a professional SEO Video Website Analysis of your site.

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