Jennifer has it basically correct. See my comments below for corrections.
Craig
At 04:21 PM 1/15/2001 -0600, you wrote:
>Ok, here we go.......
>
>We will start with basics...all network addresses end in 0.
Sort of true. All *classful* network addresses end in 0, but VLSM networks
can end in other numbers. For example, it's completely possible to have a
network address of 200.200.200.64 if there are 2 or more bits of subnetting.
>Whether they have 1,2,3 zero's depends on whether it is a class A, a class
>B, or a class C network
>address...
>class A 0-127, which is x.0.0.0 , as long as the x, is between
>0-127, it is a class A "network address".
Actually, 127.x is reserved for loopback.
>class B 127-191, which is x.x.0.0, as long as the "first x" is between
>127-191, it is a class B "network address."
>class C 192-223, which is x.x.x.0, as long as the "first x" is between
>192-223, it is a class C "network address."
>
>You don't need to worry about class D or E. They are for experimental
>purposes and they have the first number set in access of 223.
E is still experimental, but D is multicast and is frequently used.
>Network addresses are assigned by internic to companies and whether the
>companies get a class A, B, or C depends on the size of the network and
>availability .
>Gov agencies usually have A's. Very large corps. usually have a B, and
>everything else has a C.
Not necessarily true. While there are many large companies with class A
addresses, most addressing today is classless. It's very common for large
companies and government agencies to have contiguous blocks of class C
addresses. So, for lack of a better example, your network allocation may
be 212.0.0.0/8.
>When companies get their network addresses, they can break them down into
>private addressing for organization within their companies, and for ease of
>management. And that's where the other numbers come from that you were
>referring to. BUT, the address class is determined by the first number,
>or the first octette.
>If your number is in binary format, you add it up to figure out what the
>class is. Do you know how to do that? If not e-mail me.
Sort of. The class is actually not determined by the first octet, but
rather by the first 2 bits of the octet. For example, routers base their
classful distinction on the initial bit pattern of 00 (A), 10 (B), or 11 (C).
>Your address of 172.5.5.0, is a class B with a network address of
>172.5.0.0.....The 5 in the third octette is from within the company and is
>the address of one of their
>subnets and is used by their router to direct traffic to that particular
>subnet within their company. Routers "out there" in the WAN side of the
>world only use the
>network addresses for routing. And you have to know what class it is, in
>order to determine how many octettes are in the "network address" . An
>address of
>192.5.4.3 has a network address of 192.5.4.0, because it is a class C, and
>therefore is of the form x.x.x.0
>
>The 4 addresses you have:
>
>130.5.32.0
>130.5.64.0
>130.5.160.0
>130.5.224.0
>
>All these addresses come from the same network, because their network
>address is 130.5.0.0. It is a class B of the form x.x.0.0 The other
>numbers direct the traffic
>to different, specific parts of that network within the private company
>that has the network number 130.5.0.0. Those other numbers are derived
>from by a process
>known as subnetting and that's a different lesson.
>
>Good Luck!
>Jennifer Cribbs
Hope this helps.
Craig
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