What's better ...more or less linking C-blocks?

[mbulox]

I'm a little confused about c-blocks, I've been reading about them but I still don't get it.

1. Are these similar to sitewide links?
2. do they have to come from websites that I own and hosted in the same ip?
3. and finally, what's better ...more or less linking c-blocks?

Cheers

[Kingof5]

C-blocks basically refer to where an IP address is located. C-blocks are like the neighborhood and sites that share it are basically your neighbors. More linking c-blocks is better.

[CleverPhD]

Hello there!

When you read an IP address it is something like 45.452.456.77 - this is the actual "address" on the internet where your website lives.  It is like your phone number.   When you put a domain on top of it the domain "maps" to the IP, it is an alias (like speed dial), they type in the name and you are sent to the right number.

The IP address has sections separated by periods.  In my example above it would be aa.bbb.ccc.dd   The "C-block" (and dont confuse that when you are at a bar and your buddy cuts in on a conversation you might be having with a cute young lady), is the 3rd group of numbers in an IP address starting from the left, or in my example 456

Usually, when the "c-block" section of the IP address of two different websites is different, that means that the websites are hosted on separate servers.   Why does this matter?   It is very easy for sites to share an IP address or even to share C-blocks.   Kind of like houses.  You can share the same IP address, would be the equivalent of a lot of people in the same apartment complex, the street address is the same.   Having the same C-block is more like you live on the same street.  Having different C-blocks is like being on different streets, or even in different zip codes or cites etc.  Not a perfect analogy, but you get the idea.  Sites with different C-blocks are seen as more "separate" than those that share a c-block.

Why does this matter?

If you get a ton of links from sites that all share a c-block - it looks like a link farm or link scheme and Google may ignore those links or could penalize them for you.  Back in the day (not that I ever did this) you would setup a bunch of sites quickly and cheaply and they would share IPs or even be on the same c-block of IPs.   You could generate a bunch of links that way.  This was obviously spammy and Google cracked down.

Note that this could be one link per website linking to you, but if all the websites were in the same c-block it looks suspicious.

So, you can get links from the same c-block - it is not like an automatic penalty, but if ALL your links are from 1 or 2 c-blocks - it looks suspicious.  If you host websites that are truly different from each other, they all produce original content and it makes sense to cross link, I would talk to your hosting company and make sure that each site is on a separate c-block - just to be safe.  You could be "linking properly" from one site to the other, but the c-block issue could make your link pattern look suspicious.

Your host might say, "Well we cant control what IP we give you", blah blah blah.  They do use different ones over time.  What we have done is had one site setup on an IP, then wait a while (few months) then get a new IP for the next one etc.  Naturally over time, your host will be getting new IPs all the time and so you can work it that way.  You will need to update your DNS settings etc, so you need to be technically astute to change IPs, again if you think you need to (it may be that you do not).

Usually, worrying about c-blocks for links is not an issue assuming that you are getting links naturally, so this conversation may become old hat, but if you are hosting sites and linking them together, it is just something to consider.

One more, you can actually do a lookup of what sites share the same c-block.  If you find a bunch of p0rn sites on that c-block or other questionable sites, that could cause an issue with your site as you are seen in the same neighborhood.  Most hosts today you do not have to worry about and/or they keep those sites on separate blocks anyway, but just something to consider.

[MickEdwards]

This is a very useful article which I hope you find of help - http://www.blindfiveyearold.com/what-is-a-c-block-ip-address

[matbennett]

More is best.

C Block refers to the "group" that an IP address links to.  Lots of domains linking from the same C Block might suggest related sites or a network.  Having your links coming from a wider spread of C Blocks is generally seen as good.

Like with most things in SEO it is not just a case of "more wins".  the C Block of a site that links to you is just one factor amongst hundreds, maybe thousands that influence rankings.  Most importantly an unusually low number compared with linking root domains can be a sign of something odd.