ifconfig - bcast for 16bit netmask

On a RedHat 6.1 box ifconfig shows eth0 inet addr:10.75.20.201 Bcast:10.75.20.255 Mask: 255.255.0.0 This is a large production network. The correct subnet is 255.255.0.0 there is no other PC with a dup address. If I ping -b 10.75.20.255 I will recieve a reply from my self only. If I ping -b 10.75.255.255 I recieve replies from all over the subnet. Does if config show the correct broadcast address? Can you manually set the broadcast?
tdyllAsked:
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helverCommented:
You can set the broadcast address...

probably the best way is to go into

/etc/sysconfig/network-scripts/ifcfg-eth0

and edit the appropriate lines...

alternatively, you can do a man ifconfig, and simply do it from the command line.
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tdyllAuthor Commented:
Thanks for the infomation on where to make the change. I am going to break out the TCP/IP books tonight but I was interested in a conformation that the correct broadcast for ip address 10.75.20.201/16 is 10.75.255.255.

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mixerfix122699Commented:
Well, it very much depends on what is defined as a "correct" address... The "classful" bcast address for a class A network is 10.255.255.255. Your net, in effect, is using the 10.75 network (as opposed, e.g. to 10.34 network) and, therefore, the bcast of 10.75.255.255 is possible (and, indeed, in use by the network).
Your Linux box seems to be somewhat misconfigured, vis-a-vis bcast. The correct ifconfig command would be:

      ifconfig ethX 10.75.20.YYY netmask 255.255.0.0 broadcast 10.75.255.255

On a redhat machine, the answer given by helver above is correct - you can set the bcat address there.
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tdyllAuthor Commented:
Good answer, Thanks for helping me confirm the fix to my problem.

As for constructive critisizm. You may want to stick to plain english. I have no idea what you meant by "vis-a-vis" and english is my first language. Think of the guy outside the USA who may learn something from your comments.

If you want to bring up RFC guidelines for non-routing address classes you need to explain it completely. Just making reference to "Class A" addressing will only confuse the less experienced.  
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