only 256 ip add in class C ???

[rahulkothari]

Address Class Dotted Decimal Notation Ranges
Class A ( /8 Prefixes) 1.xxx.xxx.xxx through 126.xxx.xxx.xxx
Class B ( /16 Prefixes) 128.0.xxx.xxx through 191.255.xxx.xxx
Class C ( /24 Prefixes) 192.0.0.xxx through 223.255.255.xxx


Each Class A Network Address contains a 8 bit Network Prefix followed by a 24-bit host number. They are considered to be primitive. They are referred to as "/8''s" or just "8's" as they have an 8-bit Network prefix.
In a Class B Network Address there is a 16 bit Network Prefix followed by a 16-bit Host number. It is referred to as "16's".

A class C Network address contains a 24-bit Network Prefix and a 8 bit Host number. It is referred to as "24's" and is commonly used by most ISP's.


the above text was picked up from one of the tutorials at blacksun.box.sk

... hey, wat does the no xxx.xxx.xxx.172 stand for ? does it directly refer to the host no, i mean, 172 is the comp no in xxx.xxx.xxx network.

If that is so then only 256 ip addresses can be assigned to CLASS C network, and the above text says dat most ISPs use class C, then each isp can have only 256 ip addresses .
ex- ISP 'abc' has 1000 customers, and it uses a class C n/w , then only 256 of its 1000 can logon at a time.

\/
/\tremely* confused.

------------------
An eye for an eye makes the whole world blind.
-Mahatma Gandhi

[Ghost_Hacker]

Yes, if an ISP uses a class C address block they will only have 254 host ips.
(the all "ones" and all "zeros" address can't be used.)

But they will have over 2 million subnets each with 254 host ips. (if given the whole class c address block.)


Remember that number of hosts is only half the problem. You must also figure number of subnets. (IE: networks)


... hey, wat does the no xxx.xxx.xxx.172


Also remember that these numbers are really in binary and not all of the binary "places" of an octet are used for the host ip. Some may make up part of the last octet of the network address.


Hope this helps http://www.PCGuide.com/ubb/smile.gif



[This message has been edited by Ghost_Hacker (edited 06-04-2002).]

[Stevie Blunder]

It's very simple. IP addresses are 32 bits, ie 4 bytes.

A class-A network owns all addresses where the first byte is a certain value. This means the remaining three bytes can spec millions of machines.

A class-B network owns all addresses where the first two bytes are a certain value. This means the remaining two bytes can spec thousands of machines.

A class-C network owns all addresses where the first three bytes are a certain value. This means the remaining byte can spec ~254 machines.

This system was designed when the Internet was small, and ways to expand the system are already being used, like dynamic IP (DHCP), local IPs, and IP-6.

Cheers,
Steve

[skhips]

I've got myself slightly confused here.

Im happy that one octet = 8 bits but that means the highest you can get is 255 as opposed to 256 if you take away 2 (ie all the 1's and all the 0's as these cant be use) youre left with 253 address.

If I'm looking at something wrong please someone point it out as I'm here to learn.

Many Thanks.

http://www.PCGuide.com/ubb/smile.gif

[Ghost_Hacker]

No your right. I made a mistake and took Rahulkothari's original value to subtrack from.

[iisbob]

There are current parts of the IPv4 series address that are reserved; ie...127, you'll never see and addy with this octet at the beginning because it is reserved for troubleshooting/verifying your TCP/IP protocol suite. { 127.0.0.1 }

Solaris is one OS that has been supporting the new IPv6 suite for awhile now, even most Linux distro's support it-just MS is behind as usual.



------------------
iisbob

There is no such thing as a stupid question; just an improper one.-my own belief

[Anubis]

Another reserved class A is the 10.0.0.0 network, it was originally ARPAnet and is now used for internal networking. Here is a good paper on TCP/IP and the internet:
http://www.garykessler.net/library/tcpip.html

------------------
I can feel the wheel, but I can't steer
When my thoughts become my biggest fear
Ah, what's the difference, I'll die
In this sick world of mine