Re: Anyone know how "network" and "broadcast" are used?

["Aaron D. Turner" <aturner best com>]

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On Thu, 14 Jan 1999 johnr ns computer net wrote:

> Does anyone know how "network" and "broadcast" are used
> within RedHat 5.0?  By this I mean, what use the operating
> system or Bind puts to then.  Do they ever get returned to
> users on the Internet? Do they serve a purpose within DNS?

John,

I assume you're refering to the /etc/sysconfig/network file?

Basically the "network" field tells Linux and your network card what IP
subnet your system is on.  Something like 205.231.11.0 would be common.
The broadcast address for a network depends on the "netmask" or network
mask.  This tells the kernel where the network ends.  Something like
255.255.255.0 would note a full class C (205.231.11.0->255) while
255.255.255.128 would denote 1/2 a class C (205.231.11.0->127).  The last
IP address of any subnet is the "broadcast" address.  This is used when a
machine wants to talk to all the machines on a subnet at once.

Now BIND being a nameserver doesn't have host names associated with the
network or broadcast addresses since they are reserved (machines can't use
them as their IP address).  Hence, there's never a case where a properly
configured nameserver returns hostnames for network or broadcast
addresses.  There are other places where BIND might use the network and
subnet masks however in the named.boot file.

- -- 
Aaron Turner           | Either which way, one half dozen or another. 
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