Hi Michael You definitely have everything correct in what you say. Period!
What I have been noticing which is technically incorrect is the reference to arbitrary assigned address space as class A, B, C or even fractional class. I see this as labels for people to make things easier. i.e. calling 10.1.1.0/24 as "Class C" I even find myself doing it as well, when I know better. It appears this is where the usage is going. Another example things being made correct by enough people using the incorrect to become the acceptable. The biggest problem I have with this is when people mix and match the two usages of Class definitions (the correct and the incorrect). david On Sun, 17 Nov 2002, Michael H. Warfield wrote: > On Sun, Nov 17, 2002 at 06:03:37PM +0100, Michael Schwendt wrote: > > On 17 Nov 2002 07:44:38 -0500, Doug Potter wrote: > > > > Actually that is a class B address. > > > > > > The first octet of a class A is 1-126 (127 reserved for loop back) > > > class B is 128-191 > > > class C is 192-223 > > > > since 172 is between the ranges of 128-191 that would make it class B > > > > Class B subnet 255.255.0.0 or /16 > > > The step from Class B to /16 is beyond me. If memory serves > > correctly, the Class B subnet in RFC1918 is 172.16.0.0/12 > > which would be netmask 255.240.0.0. > > No no no... This is totally wrong. > > RFC 1918 has nothing to do with the old and deprecated classful > address system. 172.16.0.0/12 is one of the ranges (that happens to > be in the old Class B address space) for private addresses. > > I've heard enough erronious information in this thread at this > point and nobody has mentioned the fact that "Class A", "Class B", > "Class C", and "Class D" no longer exist for any intent and purposes. > The Internet now runs on CIDR. Classless Inter Domain Routing. > > I've seen too many people arbitrarily refer to a /24 (CIDR notation) > at being a Class C. This is also WRONG. The old Class C addresses were a > /24 netmask (255.255.255.0 - 24 bits in the network field) and in the > address range of 192.0.0.0 through 223.255.255.255. An address of > 172.16.10.0/24 is NOT a Class C nor was it ever. It meets the netmask > specification but is not in the Class C range. > > It's in the Class B address space but, assuming that it's a > /24 netmask, it's not a Class B network either because it doesn't meet > the netmask specification. At most, it's a SUBNET of a Class B > network, under the old deprecated classful system. It also happens > to be a part of the private address space allocations, which is something > else, yet again. > > Old Notation: > > 0.0.0.0 - 127.255.255.255 Class A range 255.0.0.0 netmask /8 > 128.0.0.0 - 191.255.255.255 Class B range 255.255.0.0 netmask /16 > 192.0.0.0 - 223.255.255.255 Class C range 255.255.255.0 netmaks /24 > > These are now, at best, default conditions for netmasks when the > netmask or CIDR bits are not specified. It would be better if we > simply DROPPED references to the old Classes entirely. I now refer > to my address space as being one of the "fossil Class B" addresses > (a Class B address allocated under the old Classful system and now > merely a /16 allocation). > > To answer another message, the number in a / number (such as /12) > describe the number of network bits in the netmask. A netmask of 255.0.0.0 > has 8 bits set so it's a /8. A netmask of 255.240.0.0 is a /12 because > it has 12 bits set (1111 1111 . 1111 0000 . 0000 0000. 0000 0000). > > The original question asked was poorly phrased and has no real > deterministic answer. The "tightest" netmask, which totally encloses > all of those addresses in the original question, is a /24 which covers > the range from 172.16.0.0 - 172.16.0.255. It could also be contained > in a /23 netmask from 172.16.0.0 - 172.16.1.255 or a /22 netmask from > 172.16.0.0 - 172.16.2.255, etc. The private address space, of which this > is a SMALL part, is specified by RFC to be 172.16.0.0 - 172.31.255.255 > which is a /12 address space (encompassing 16 of the old Class B network > addresses) and which also encloses the entire address range listed > in the original message (plus a WHOLE lot more). > > The best answer I could come up with is that it is PROBABLY > contained within a /24 address space (netmask 255.255.255.0) but may > be contained within a larger address space. The specific addresses > in question are in RFC allocated private address space and may not > be routed on the Internet (which wasn't asked but may be relevant). > > Mike > -- > Michael H. Warfield | (770) 985-6132 | [EMAIL PROTECTED] > /\/\|=mhw=|\/\/ | (678) 463-0932 | http://www.wittsend.com/mhw/ > NIC whois: MHW9 | An optimist believes we live in the best of all > PGP Key: 0xDF1DD471 | possible worlds. A pessimist is sure of it! > -- redhat-list mailing list unsubscribe mailto:[EMAIL PROTECTED]?subject=unsubscribe https://listman.redhat.com/mailman/listinfo/redhat-list
