subnet masks.....

[Hans]

Hi

I've just learned a lot (more) about subnet masking....
now there still remain two questions.
1. it is true that a class a,b or c ip addres can be determend by the first
octet. now i learned that a class a,b or c ip adress can be used with any
class a,b or c subnet mask. Is that always true?? I learned at an HP course
that some HP unix servers won't allow that.
a class a ip addres must be used with a class a or lower subnet mask.

2. how can it be that my ppp adaptor has an subnet mask of 255.255.255.255
???? VVVV look VVVV

Connection-specific DNS Suffix . :
Description . . . . . . . . . . . : 3Com EtherLink III ISA
(3C509/3C509b
) in Legacy mode
Physical Address. . . . . . . . . : 00-60-08-EF-FD-45-F4
DHCP Enabled. . . . . . . . . . . : No
IP Address. . . . . . . . . . . . : 200.2.2.2
Subnet Mask . . . . . . . . . . . : 255.0.0.0
Default Gateway . . . . . . . . . : 200.2.2.1
DNS Servers . . . . . . . . . . . : 200.2.2.3
201.2.2.4

PPP adapter hccnet:
Connection-specific DNS Suffix . :
Description . . . . . . . . . . . : WAN (PPP/SLIP) Interface
Physical Address. . . . . . . . . : 00-67-87-00-00-00
DHCP Enabled. . . . . . . . . . . : No
IP Address. . . . . . . . . . . . : 76.221.65.3
Subnet Mask . . . . . . . . . . . : 255.255.255.255
Default Gateway . . . . . . . . . : 62.251.45.2
DNS Servers . . . . . . . . . . . : 76.221.0.8
76.221.0.7
NetBIOS over Tcpip. . . . . . . . : Disabled

C:\>

[Jon_Hildrum]

Yes, the first few bits determines the class of the network.
Some systems takes advantage of this and do not really need a netmask for a
class A, B or C network.

if the first bit in an ip address is 0 then it is a class A network.
If the the first two bits are 10 then it is a class B network
if the first three bits are 110 then it is a class C network

Try my page here
http://www.hildrum.com/IPAddress.htm

--
Jon Hildrum
DTS MVP
Jon_H...@msn.com
www.hildrum.com
"Hans" <han...@zonnet.nl> wrote in message
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