I haven't talked about IP addresses for a while (and never in this blog). Since I've been asked several times recently about them, I think it's a good time to talk about them.
What is an IP Address?
Computers "think" in numbers, not words and letters. Humans tend to be the opposite. In order to deal with this, programmers and technicians have been creating technologies that translate between the two since shortly after computers were invented. Programming languages are an example of this.
Another example of this is DNS, or Domain Name Services. See, your website really can't be found at your domain name - it's found at an IP address. The domain name is just a human-friendly way of finding the IP Address. Think of it like a telephone number. It's much easier to remember someones name than a telephone number, but your telephone doesn't understand names, just phone numbers. So we invented phone books. You look up the name you remember in a phone book, which gives you a phone number that the phone system can understand. DNS is like a phone book for the internet.
If you type in http://www.mcanerin.com/ into a browser, you don't go over to my company site right away. Instead, your browser looks up the name in a DNS server and the DNS server tells it an IP Address (in this case, 220.127.116.11) that matches the domain name. Then the browser can go to the right website.
So the bottom line is that an IP address is your websites real address on the internet. Now, there are just so many IP Addresses in the world, so people have figured out ways that more than one website can share an IP Address. In this case, after the browser gets the IP Address, it goes to the webserver and also gives it the domain name it's looking for. The server then sends the requested site. This is like having one phone number for your home, rather than one phone number for each family member living at your home. You have to phone the house, then ask for who you want to talk to.
When you have each person with there very own phone number, it's more expensive, often unnecessary, but has some advantages, like your personal cell phone. The same applies online.
Dedicated IP Address VS Shared IP Address
A Dedicated IP (sometimes wrongly called a "static" IP by some web hosts) is an IP address that only points at one website. A Shared IP is an IP address that can be shared by more than 1 website.
Now, search engines don't usually care about IP addresses - they index you based on your domain name. That's why having more than one domain name for a site can confuse them.
Note on Dynamic and Static IP Addresess
When you use your ISP to connect to the internet, you will often get what is called a "dynamic" IP, which means basically that it changes. Most ISP's have a big pool of IP addresses and they just hand a random one out to you whenever you connect.
A static IP is simply an IP that you have each time you log in - it doesn't change. You really don't need a static IP for just surfing the net, but if you host your own server at your home or office then it's usually best to get a static IP address.
There are ways to host websites with a dynamic IP address. I hosted mcanerin.com for years at home on a dynamic IP address and ranked very well, thankyouverymuch. I just ran a script that automatically checked my IP constantly, and when it changed, the script would update my DNS server with the new IP and my site was back up and running again, often within a minute or so. This is a good example of why IP really doesn't matter as much as some people think it does for search engines.
Keep this in mind when some tech tries to tell you that your website is doomed if you switch servers or IP's. Nonsense. I used to switch IP's as often as several times a day without any problems :)
Geolocation by IP
There are, however ways a search engine will use your IP Address. Neither are directly for ranking purposes. They are additional processes that Google applies to sites during the ranking process. The first is Geolocation.
Since IP addresses are assigned to webhosts, and then given to that webhosts clients, a search engine can lookup where that webhost is, and therefore know where, approximately, your website is hosted. This is one way that Google knows your site is from the US, Canada or China. Google will give websites that it knows are from the UK a boost in results shown to searchers from the UK, on the assumption that they would probably consider UK sites to be more relevant to them. This is almost always a good assumption.
The problem is that if you are a UK company but host your .com in the USA for some reason, you will be considered a US site, not a UK one. Dealing with issues like this is actually my specialty, and I assure you there can be some tricky aspects to it, especially if you have sites for different areas of the world but one CMS that controls them all. So it's important to know where your IP is Geolocated to.
IP Address and Spam.
The second problem is a little more insidious and difficult to pin down. IP Addresses, being known physical locations, are a better method of detecting search engine spam than domain names, which can be moved around very quickly and are cheaper than hosting. So search engines look at IP Addresses (among many other things) during spam checks. This can cause problems for some sites.
The thing is that if you have a hosting account and decide to use it to create a link networks of thousands of sites, then all of those sites will either have the same IP address, or will be withing the block of IP addresses that your website host has available. Website hosts are typically assigned a Class "C" or part of a Class "C" to use. I'll explain what this is in a moment.
What Google knows at this point, however, is that chances are that a whole bunch of sites on the same IP or within the same Class "C" IP Address space have something in common" At the very least, they are hosted by the same webhost in the same location together. This may mean nothing, or it may mean that they are all owned or controlled by the same person or persons. In short, if they start linking to each other, the links may not be independent.
There is no guarantee of this, of course. Some towns (and small countries) only have one host, and therefore they all share a Class "C".
What is a Class "C" IP Address Range?
What's a Class "C", you are still asking me? Ok, it's actually really easy.
A typical IP Address has 4 sets of 3 numbers. In cases where some of the numbers are 0, you can leave them out. So the IP address for mcanerin.com is: 064.034.120.055, or it's sorter form, 18.104.22.168. Since firewalls are usually used to block the long form in favor of the short form, it's usually a waste of time to try to use the long form.
Let's look at this IP address. If we replace the numbers with X's to symbolize a generic IP Address, it looks like this: XXX.XXX.XXX.XXX - now, each of these sets of three X's is a Class. If I now change the X's to the Class, it would look like this: AAA.BBB.CCC.XXX.
The X's at the end are correct, they are not the "D" class or anything like that. Now, do you see the "CCC" section? That's the Class "C" number. In my case (064.034.120.055) the Class "C" address is 120. This means that other sites that have a 120 right there (XXX.XXX.120.XXX) would be considered related in some way.
Relationships Can be Good (or Very Bad)
By itself, a relationship means little. Linking or being linked to is a relationship, as well. So is being in the same country, having similar WHOIS contact information for your domains, and all sorts of other things.
The problem is that in general, the more relationships that are involved, the more likely a site will be considered directly related. Google really doesn't want to show more than one directly related site in any particular SERP - it's not really fair for have the same owner have 5 of the top 10 slots, for example. Additionally, links from sites that are related to you should (and usually do) count for less than links from total strangers.
This means that you should be aware of your Class "C", and of the Class "C"'s of other sites you may own. This sounds like I'm telling you how to spam better, but here is why I recommend this even for the most milky white of white hat sites.
Real Life Example of Why You should Care About Your Class "C"
I had a client, who had 2 sites. They were both in the same general topic range, and hosted on the same Class "C". One site was on the topic (for example) of "New York Lawyer", and the other was one the topic of (for example) "Lawyer Resources". There was no overlap in content, and the target audiences were completely different. Additionally, the keywords for each site were also different. Or so we thought.
It turns out that "New York Lawyer" and "Lawyer Resources" have something in common: the keyword "Lawyer", even though neither site was actually pursuing that term! Now what we had was 2 sites that were related (on the same Class "C") and, in Googles mind, relevant for the same keyword ("Lawyer"). One site dropped off the SERPS for almost everything except a few long tail terms, and the other lost rankings, as well. Why? Because multiple related sites on the same topic hit a spam filter. That's not a problem in theory, except Google assumed a keyword neither site was pursuing to be the issue.
The fix was to totally separate the sites. We moved them to 2 different Class "C" addresses, and just to be sure changed the WHOIS data to the second owner (NEVER fake WHOIS data - it's against the law). This fixed the problem, and both sites now rank well for their respective keywords. If you check the shared keyword, Googles duplication filter kicks in and only the site with the highest link pop shows up - which is exactly the type of behaviour I would expect, and have no problem with.
So keeping your sites on difference Class "C"'s is a good idea, even if you are not inclined to spam at all.
Why You Should Care About Other People's Class "C"'s
Here is another issue: what happens if you are on a shared IP with other sites that are going after your keyword? You now have 2 relationships with them, whether you know it or not. This can cause problems even if you are totally innocent. It's a good idea to check the other sites on shared IP addresses for this reason, and make sure none of them are competitors or otherwise related to your keywords. Same with Class "C"'s to a lessor degree.
Finally, what if you have sites on 2 different Class "C''s, but the same people link to both of your sites? Shows a relationship? Of course! But here is another scenario you may not have thought about. What if the people pointing at your site have relationships with each other?
What if you have 10 websites pointing to you, but they are all from the same IP? Or same Class "C"? Of course links from related sites won't pass on as much PR as unrelated ones. Geez, things just keep getting more complicated, don't they?
So What Do I Do?
Well, you have to host *somewhere*. And you can't really control the IP's of everyone who links to you. Even a link that passes on less than the full PR is still passing on PR. At some point you just have to decide to stop worrying and get on with marketing your website. Having the "perfect" IP address won't rank you for anything. It's just a technical detail that can bite you on occasion.
In general, people still rank well for all sorts of things, even if they don't even know what their IP address is, so this isn't the end of the world. I would personally only worry about it if:
- You have more than one site on a topic that could even be slightly related ( If so, consider merging them)
- You are considering begging/trading/buying links from groups of sites
- You have an inexpensive, popular host (spammers like cheap hosting)
If any one or more of the above are true, then you should to start paying attention to relationships, including links and IP Addresses. Relationships are the currency of the internet, and it's much better to have good relationships with others than bad or questionable ones.
Some tools to help you: