What exactly is "Class C" and how do you check/verify it?

[Kush]

I'm hearing the term more and more these days, mostly from you Jay, but it's also thrown around by some other people.

Can anyone explain it to me?

[Cleo]

Class C network address is a non public address.

Like the fact that the IP of the computer that I am typing this from is 192.168.1.69. You would never be able to find me because this is a non public address. My router routes my public address to my compute's private address. If I wanted the web server that is running on my computer to be publicly available I would have to go into my routers settings and map port 80 to 192.168.1.69.

There are a few ranges, the more common ones are 192.168.1.1 to 192.168.1.254.

[Greenguy]

I thought a Class C referreed to the 1st 3 parts of the IP address - like the Class C that I am sharring is:

66.115.135.XXX

Class B would be all the IP's on:

66.115.XXX.XXX

Class A would be all the IP's on:

66.XXX.XXX.XXX

I also heard they are thinking of going to 6 sets if numbers in the IP's because they are running scarce (I guess a few University's got Class B's assigned to them back in the day & they won't let them go, so that means one University owns the rights to 250,000 IP's

I could be wrong......

[Cleo]

Math confuses me.

You may be right about the actually numbers, not sure. Here is a page one it. http://support.wrq.com/tutorials/tcpip/ipadd1.html

All I know is Class C is reserved for private addresses.

That is IPv6 and is suppose to replace the IP addressing that we use now since we are running out of addresses.

One little problem, all the routers in the world will need to be upgraded. Also all the OS will need to be upgraded as well. Mac OS X supports it, not sure what other OS do.

[DangerDave]

Class A - This class is for very large networks, such as a major international company might have. IP addresses with a first octet from 1 to 126 are part of this class. The other three octets are used to identify each host. This means that there are 126 Class A networks each with 16,777,214 (224 -2) possible hosts for a total of 2,147,483,648 (231) unique IP addresses. Class A networks account for half of the total available IP addresses. In Class A networks, the high order bit value (the very first binary number) in the first octet is always 0.


Class B - Class B is used for medium-sized networks. A good example is a large college campus. IP addresses with a first octet from 128 to 191 are part of this class. Class B addresses also include the second octet as part of the Net identifier. The other two octets are used to identify each host. This means that there are 16,384 (214) Class B networks each with 65,534 (216 -2) possible hosts for a total of 1,073,741,824 (230) unique IP addresses. Class B networks make up a quarter of the total available IP addresses. Class B networks have a first bit value of 1 and a second bit value of 0 in the first octet.



Class C - Class C addresses are commonly used for small to mid-size businesses. IP addresses with a first octet from 192 to 223 are part of this class. Class C addresses also include the second and third octets as part of the Net identifier. The last octet is used to identify each host. This means that there are 2,097,152 (221) Class C networks each with 254 (28 -2) possible hosts for a total of 536,870,912 (229) unique IP addresses. Class C networks make up an eighth of the total available IP addresses. Class C networks have a first bit value of 1, second bit value of 1 and a third bit value of 0 in the first octet.

DD

[Cleo]

Subnets really confuse me,
http://support.wrq.com/tutorials/tcpip/subnet1.html

I also often see 10.0.0.1 used for private addressing behind a proxy server. I've never understood that at all.

Basically I deal with IP addressing the same way I deal with JavaScript in that I've learned what works and enough to know what to put where, but don't have a complete understanding of why.

I do know that if you are setting up a network behind a router you can start with 192.168.1.2 on the computers and keep on adding 1 to each computer so that the next one would be 192.168.1.3 and so on and so on up to 195.168.1.244. The subnet stays the same at 255.255.255.0 and the router or gatway is 192.168.1.1.

[Kush]

So how is different Class C relevant in terms of google?

Has anyone done extensive testing to show the benefits of being linked up from "different Class C" servers?

[Cleo]

Does Google even know what Class C address you are on?

I've always understood that Class C was always only used for private addressing.

[Kush]

Originally posted by Cleo
Does Google even know what Class C address you are on?

I've always understood that Class C was always only used for private addressing.

See, I don't know.

I'm wondering if people say they have sites on different Class C's just to make their trading of links appear to be more valuable, or if it really does make a different.

I guess in some sense this is similar to people saying they have sites on different IPs. Is it really an advantage?

[Greenguy]

I only know rumors, but from what I'm told, it's bad to have all your domains on the same Class C because if Google sees you linking to other domains that are all on, for example, 66.115.135.XXX they can assume that you are linking to other sites that you own or are in your network & hold that against you (knowing that they are all in your own little hub)

But if you link to domains on other Class C's, they treat them as legit link trades & thus hold them in a higer value.

[DangerDave]

Most of this stuff is anecdotal and speculative... but as they say it doesnt hurt to do it and may offer you some longer term security.

DD

[Linkster]

The only "intelligent" argument I've heard about separating Class "C"'s involved the ability to do a hand (or possibly even an automated) whois by the SE. If that is not done then you harm all of the sites on virtual hosting where single IPs are shared among domains.

But just in case I keep a spare Class C around

[xxxjay]

Originally posted by DangerDave
Most of this stuff is anecdotal and speculative... but as they say it doesnt hurt to do it and may offer you some longer term security.

DD

Exactly - it's always better to plan ahead, than get bit in the ass.