Help with Network Address Math

The smaller the bit mask number (in this case /16 and /24) the less specific
the network.

Gilbert

-----Original Message-----
From: plug-discuss-admin@lists.plug.phoenix.az.us
[mailto:plug-discuss-admin@lists.plug.phoenix.az.us]On Behalf Of AZ Pete
Sent: Thursday, August 07, 2003 1:11 PM
To: plug-discuss@lists.plug.phoenix.az.us
Subject: Help with Network Address Math


Calling all network gurus :)

My IP network address math is rather rusty (it's been a long time!!). I
have need to calculate whether a given client
IP address is within a given network. Additionally, if there are a list of
given networks, which one is the most
specific. I need the math formulas to calculate these figures for use
within an application.

Examples:
Given the network: 192.168.1.0/24
Given IP address is: 192.168.1.100

What is the formula to determine if this client's IP address falls within
the network's range.

Further example
Given these networks: 192.168.1.0/24 and 192.168.0.0/16
and the client IP of: 192.168.1.100

In this case the client's IP falls within both networks. What is the formula
to determine which network is the more
specific one?

Any help would be most appreciated.
Thanks,
Peter
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