Talk:Classful network/Archive 1

What?

Say.. this article needs a couple of introductory sentences explaining what the hell it is about. As a general, non-tech, liberal arts reader, I have no idea what any of this article means. I understand that the more technical stuff is going to be incomprehensible to me, but perhaps just one or two sentences at the beginning to put it into context or something? Torgo 04:47, 31 March 2007 (UTC)

the zero address range

An expansion of the purpose of the zero-address range by someone more in the know than I would be greatly appreciated. -- Jon Dowland 16:40, 16 January 2006 (UTC)

If you are speaking of subnet zero, that's an artifact of classful routing, in which you don't always have the subnet mask available but have to infer it from the first few bits. For example, without a subnet mask or CIDR length prefix, is 10.0.0.0 a "class A network", or is it subnet zero of a 24-bit prefix? You can't tell by looking at the address alone.

With CIDR notation, the first is 10.0.0.0/8, but the second is 10.0.0.0/24. There's no ambiguity for the all-zero subnet if you always know the mask. Hcberkowitz 22:51, 25 June 2007 (UTC)

Class E

Does anyone know what the Class E addresses (240.x.x.x-254.x.x.x) were reserved for? Experimental is what I seem to have found..anyone know what was meant by this?--Kcbnac 06:32, 13 October 2005 (UTC)

As a participant in IETF addressing work, I've never heard anyone explain the purpose of Class E, but there are so many implementations that would reject it as an invalid range, no one has ever really tried to make it work. Hcberkowitz 22:53, 25 June 2007 (UTC)

switch or router?

the edit made on this date 21:58, 11 September 2006 203.145.184.222 seems awry.

they changed switches to routers and it seems to have stuck. note that they also changed the year from 1982 to 2006 etc etc.

Yeled (talk) 02:26, 24 January 2008 (UTC)

192.168 Class

What class is the 192.168 subnet? On the special ranges table it lists it as a class C with a /16 mask, while the "Class ranges" table says that a /16 netmask is a class B. Which is it? Same goes for 192.18, I guess... --Poromenos 19:43, 23 June 2007 (UTC)

With due regard that classes are obsolete, 192/8 (in current notation) or 192.x.x.x are class C. 192/8 is also called the traditional Class C space, or, among service providers, "the swamp". At one point, before CIDR, addresses in 192/8 took up half the global routing table, and prefixes of /24 or longer (i.e., mask 255.255.255.0, 255.255.255.128, etc.) took up half of 192/8. The latter part of the "swamp" was called the "toxic waste dump" in CIDR slang.

192.168/16 is designated as private address space, not routable on the Internet. 192.0.2.0/24 is reserved for specialized testing.Hcberkowitz 22:48, 25 June 2007 (UTC)

While 192.168/16 appears to be a Class B subnet, it is actually a collection of 256 separate Class C subnets. The notations 192.168/16 is therefore somehow inaccurate, the correct approach would be to list the 256 subnets indivdually (192.168.0/24, 192.168.1/24, 192.168.2/24, ..., 192.168.254/24, 192.168.255/24).

This set of subnets was useful before CIDR appeared. With CIDR, the 192.168/16 range can indeed be used like a Class B subnet or whatever subnet sizes the user requires.

Before CIDR, some devices had hard-coded subnet class assignments. So they regarded 10/8 always as Class A, and it was not possible to split this subnet into smaller subnets. So 192.168/16 was created, for people who needed a number of small separate subnets. --80.134.14.19 (talk) 15:25, 9 April 2008 (UTC)

bits or bytes?

The third sentence in this article says, "Each class, coded by the first three bits of the address, defined a different size or type (unicast or multicast) of the network."

Perhaps that should be bytes (octet), not bits. —Preceding unsigned comment added by 116.197.178.83 (talk) 01:51, 9 December 2008 (UTC)

No, it should say "coded by the first *few* bits of the address", see the first table which gives the leading bits for each class (0, 10, 110, 1110, 1111). Gvanrossum (talk) 20:37, 19 March 2009 (UTC)

End of Class A range wrong?

Not sure if I am right and guess this is the right place to bring it up, but I thought a class A address range ended at 127.0.0.0 in (ddn) not 126.0.0.0 as stated in the article?

Shouldn't the end of the Class A range (under "Useful tables") be 127.255.255.255 instead of 126.255.255.255? --195.37.212.230 (talk) 10:08, 21 January 2008 (UTC)

Oops.. 127.* is a special address range. --132.199.235.61 (talk) 17:28, 21 January 2008 (UTC)

The correct Class A range is 0.0.0.0 to 126.255.255.255, 127.0.0.0 to 127.255.255.255 is reserved per RFC 1700. —Preceding unsigned comment added by Phidjit (talk • contribs) 20:31, 12 March 2008 (UTC)

That's right so whatever retard put in that the range ends at 127.255.255.255 needs to recheck their data. 127.x.x.x is reserved for loopback and does not have a class. this page is another instance of how wikipedia supports whatever people want to say based on whether they're wrong or not. —Preceding unsigned comment added by 134.29.213.204 (talk) 20:23, 3 March 2010 (UTC)

The definition of class A addresses is that the leading bit is zero. That is the only criterion, and therefore 127/8 is a class A block. This has nothing to do with the actual use of the addresses. There are other addresses that are reserved as well, and they are still class A or whatever class addresses. No RFC has removed 127/8 from class A somehow. When a 127.* address is assigned to an interface it has always automatically received a /8 subnet mask. Kbrose (talk) 21:12, 3 March 2010 (UTC)