C class IP definition

Hi,

I'm trying to figure out what the definition of a C Class IP range is and, surprisingly, I'm having trouble finding a consistent definition.

One SEO tool at http://www.webrankinfo.com/english/tools/class-c-checker.php?tab_url=foreverfavors.com%0D%0Achococheer.com that I found for checking C Class IP ranges of domains gives the following results:

URL: chococheer.com / IP Address: 66.235.193.158
URL: foreverfavors.com / IP Address: 66.235.193.158
Class C: 66.235.193

Implying that the C class is the first 3 number blocks of the IP address like A.B.C.D

While, another SEO tool at http://www.webmaster-toolkit.com/class-c-checker.shtml?address1=foreverfavors.com&address2=foreverfavors.com
gives the following results:

The 2 domains are NOT hosted on the same Class C IP range.
foreverfavors.com is hosted on Class A IP 66.235.193.158
foreverfavors.com is hosted on Class A IP 66.235.193.158

According to sites that focus on the syntax of IP addresses outside of an SEO context, the C class has an IP range of 192.0.1.1 to 223.255.254.254. (see: http://www.computerhope.com/jargon/i/ip.htm)

This leaves me wondering: are there 2 different definitions of class C ip ranges and which one is relevant to SEOs? My guess is that the first example is most relevant to SEOs since it involves sites that may be on the same server.

Thanks,
Brian.

 

http://www.webopedia.com/TERM/C/Class_C_network.html

 

Of course, the situation is rather complicated by the fact that originally networks were designated like this:

1-127.x.x.x - class A
128-191.x.x.x - class B
192.x.x.x - class C

Since CIDR (classless inter-domain routing) came into place this is basically obsolete, but this is why you're having trouble finding a definite answer to your question - there any multiple right answers!

When someone refers to a 'class c' what they normally mean is a /24 - the first 24 bits of the address being the network part, the rest being the host part.

IMO all this stuff about 'seperate class Cs' is a load of tosh - Google can easily look at the whois databases and see who the IPs are allocated to. What you really want is multiple IPs on multiple different allocations - there's no way for Google to connect these.

 

I see. So, the 2 sites in my second example are using the old notation. That makes more sense. Too bad they don't update those sites because it certainly got me pretty confused.

Thanks for the answers!

 

Hi forkqueue,

What part of the whois record should I be looking for to make sure sites are on different allocations and is there any API or anything to write a script to check this?

Thanks,
Brian.

 

For ARIN allocated (American) addresses the formats for the IPs vary.

sam@io:~$ whois 216.9.35.50
NetHere Inc. NETHERE-3 (NET-216-9-32-0-1) 
                                  216.9.32.0 - 216.9.47.255
Digital Point Solutions NTHR-DIGITAL-POINT (NET-216-9-35-48-1) 
                                  216.9.35.48 - 216.9.35.63

Code (markup):

From this you can easily see the range allocated to NetHere, who host Digital point on their network.

RIPE (European) allocated IP addresses are a standard format, but it's not always so obvious to see the LIR (the people the IP address has been allocated to). Normally by doing a whois on a larger part of the range you can find them though - they'll be denoted by an 'org:' tag, eg:

inetnum:      212.85.224.0 - 212.85.255.255
org:          ORG-Cl11-RIPE

Code (markup):

I'm assuming you won't be hosting anything in Asia, which is handy, because with APNIC you're often lucky to have any whois info at all for an IP!