Pinging 255.255.255.255 for trouble shooting

[leafar1988]

Some one mentioned to me that you could ping the broadcast address of 255.255.255.255 to discover if there are any reachability issues.

I am having a hard time picturing this in my head. Can someone please explain to me how exactly pinging all 255's help with troubleshooting? Thanks.

[InayathUlla Sharieff]

Leafar,

I am not sure on what context the person have told you to use the ping for the broadcast address, as we need to understand why he said so.

255.255.255.255 is a broadcast address, you are sending a ping to every device on your local network and you will get a reply from every device. The ping command is only showing the first reply it gets, in your case your own PC (127.0.0.1 is loopback) was the quickest. If you use a packet sniffer (like Wireshark) you will be able to see all replies.

Some devices will reply to a normal ping but will not reply to a ping sent to a broadcast address. This is to prevent an exploit called a Smurf attack.

255.255.255.255 will also broadcast to every device on the internet. For obvious reason this is blocked, the message will not leave your local network.

Hence it is not a good way to troubleshoot the issues. Kindly have a step approach followed to troubleshoot the issue following the OSI model/method of troubleshooting and you will be good after that.

Hope this helps.

REgards

Inayath

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[devils_advocate]

Inayath has provided some good information there (+5).

I would question what you are trying to troubleshoot.

ICMP is a basic troubleshooting tool.....i.e. can you ping anything on your local L2 subnet.....can you ping something in another subnet.

Its good for reachability tests but its not the only troubleshooting tool there is.

ICMP is often allowed on firewall rules so you may find a ping works but a HTTP request may not so it entirely depends on what the issue is.

Use ping by all means, but don't rely on it as the only troubleshooting mechanism.