Comments on: How a Broadcast Address Works

By: richard

richard — Tue, 15 Nov 2011 01:05:54 +0000

Thanks so much for this explanation. Keep em coming.. Hey…. by the way ..I am really thinking about making a career move .. I currently work in real estate but have been self educating in networking over the last couple months and seem to have a knack for it.. I was told by many certification schools that it is really a good job market out there but that I will need a few certifications to break in…. I know they want to make some sales and am a little skeptical….They told me that if I got my net+,ccna and mcitp I could easily find a job and in a few years be making over 50k. Would anybody out there care to comment about this.
Thx so much and god bless…

By: saravanan

saravanan — Wed, 31 Aug 2011 20:30:07 +0000

@Vern: for router to broadcast to hosts in 10.1.2.0/24 subnet, ‘ip directed-broadcast’ has to be enabled on the interface. by default, it is disabled.
http://www.cisco.com/en/US/docs/ios/12_3/ipaddr/command/reference/ip1_i1g.html#wp1081245

By: Vern

Vern — Thu, 11 Aug 2011 16:05:12 +0000

QUESTION: If two subnets (10.1.1.0/24, and 10.1.2.0/24) are connected through a router/gateway; and a host (10.1.1.100) sends a frame to a “10.1.2.255″ destination address; will it get passed (i.e., routed) to the connected domain and get distributed (broadcast) there?

This is a corner case of interest, that currently seems ambiguous to me. Anyone that knows for sure, please advise. Thank-you.

By: raghava

raghava — Mon, 11 Jul 2011 14:39:35 +0000

i want to find who sent the broadcast message?
i mean that from which system the message was came?

By: Peter

Peter — Tue, 25 Jan 2011 18:45:56 +0000

Regarding the discussion on classful networking:

Classful networks were abandoned in 1993 in favor of CIDR block allocations.

Before 1993, Lieven and Daniel would be correct (almost ) : class-A networks were from 0.0.0.0 to 127.255.255.255, B from 128.0.0.0 to 191.255.255.255, etc…

After 1993, CIDR blocks allowed for a more efficient allocation of addresses by allowing the break up of larger A’s and B’s into smaller and more incremental segments than the traditional classes allowed. You should know this as slash notation (192.168.1.0/24)

In modern networks, Class A, B and C’s are essentially colloquial terms to describe the major CIDR blocks at /8 (A), /16 (B) and /24 (C).

So in the above example of 192 addresses, while maybe not as clear as he could be if he used CIRD slash notation, he is in fact corect given that the article was written after 1993.

By: admin

admin — Thu, 21 Oct 2010 22:25:59 +0000

Lieven- this was a simple syntax error in my image editing software. Although, I’ll say that I appreciate your comment as it has led me to fix the error

And thanks Daniel, not sure why I didn’t read your comment better the first time.

By: Lieven

Lieven — Tue, 19 Oct 2010 09:22:13 +0000

Clearly this is written by someone is learn(ing)-networking.com
I’m glad that someone (Daniel) already seen this huge mistake about classes. Classes refer to IP addresses NOT subnetmasks.

By: Marcelo

Marcelo — Thu, 01 Jul 2010 13:17:32 +0000

If “a switch is pretty much just a router, so yes, it will stop the broadcast” how can the devices receive the broadcast on a switched network? I mean, if my pc sends a broadcast packet, the first thing the packet will hit on a switched network, will be the switch and if the switch stop the broadcast, how the other host are supposed to receive the broadcast?

By: lopata

lopata — Sun, 23 May 2010 20:55:00 +0000

nice tnx

By: rastamannen

rastamannen — Tue, 13 Apr 2010 11:58:40 +0000

Hi!

If u have host adresses in the range .0 – .255
Can i use .255 wich is the broadcast adress in a WAN’s broadcast?