More of IP/Subnet stuff,PLEASE!

[Doug Sherman [MVP]]

OK - I meant largest 32 bit number. I agree that largest vs. smallest is
not a very good way to characterize a subnet mask. Think of it as the
smallest subnet mask (or the one that gives the smallest number of hosts) if
that helps. Like most math based concepts, there are many different ways to
explain subnetting. Some explanations will click for you, some will seem
unnecessarily complex, and some will make no sense at all. The trick is to
find the ones that click for you.

Also, notice that just because your subnet can accommodate more hosts than
you need, that does not mean that your DHCP server has to be able to give
out all the possible addresses. It is common and often necessary to
configure the server to exclude certain addresses or ranges of addresses
within the subnet. The reason for this is not likely to be a desire to
match the number of available addresses to the number of hosts, but you
could do that if you wanted to. However, you could still manually assign an
excluded address to a computer and it would work fine because it's all the
same subnet.

Doug Sherman
MCSE Win2k/NT4.0, MCSA, MCP+I, MVP

 

[Alon Brodski]

Hey!

Thanks for the advice!
I just want to dot the i's and cross the t's here.
So basically a subnet mask is not a predefined No. of hosts ,but a range
that is always larger than actual amount of PCs,right?

What I don't get is why you wrote :"The implied interpretation should be
something like 'what is the largest subnet mask which will allow you to
have at least X hosts."
The largest subnet mask in my case would be 255.0.0.0 since it's an A class
IP address (84.94.158.20) with
over 16,000,000 hosts.But it contradicts the whole idea of a subnet mask (to
make it easier to find a specific host within that huge amount of
hosts)...Therefore,logically,it would the SMALLEST subnet mask which will
allow me to have X No. of hosts.Unless you meant the opposite of what I
mean,ie. largest subnet mask No. with smallest range.I don't compare
255.0.0.0 and ,say,255.255.255.0 to tell that 2nd is bigger than 1st.I meant
the IP address range of a subnet behind it.

Alon

 

[Alon Brodski]

Hey!
Thanks again for your advice...could you tell me something about multiple
subnet mask for certain IP address as a way to make an address range smaller
or closer to No. of hosts? I thought that for each IP address we only can
have ONE subnet mask

Alon

 

[James Egan]

The largest subnet mask in my case would be 255.0.0.0 since it's an A class
IP address (84.94.158.20) with
over 16,000,000 hosts.

No-one uses classful addressing anymore.
http://www.tcpipguide.com/free/


Jim.