New Page 1
Site Navigation
Home
Statistics
Classes
Blog
Interests
PC Hardware For Sale!
Forums
 
Photographs
Photos
POTW Archives
Picture Gallery
Events
Party 10-28-06
Party 08-05-06
Virginia Trip 06-26-06
Colorado Trip 04-20-06
Party 01-20-06
Drinking with Cops
Pumpkin Carving 2005
Party 10-08-05
New House Pics
 
Video Games
GTA: San Andreas
Half-Life
Half-Life 2
Half-Life 2 DM
Half-Life 2 Episode 1
Half-Life 2 Episode 2
Half-Life 2 The Lost Coast
Prey
Quake 4
Tomb Raider: Legend

Tutorials
BitTorrent
DVD Ripping
Firefox Search Engines
Firefox2 Search Engines
Kazaa
Windows Server 2003
DHCP Service
DNS Service 
FTP Service 
NTP Service
WINS Service
WWW Service 
 
Stories & Editorials
The Pictureframe PC
The Macin-Clock
DJDingo's First Flight
How to speak "boonie"
DJDingo's Favorites Archive
Why I will never ship through USPS again
Loopback Mayhem
Problems with having a website
Things DJDingo Hates
The Modem Mod
Projekt Revolution Tour
My Jury Duty Experience


First Looks
Internet Explorer 7 RC1
Internet Explorer 7 Beta 3
Windows Media Player 11
Office 2007 Beta
Internet Explorer 7 Beta 2
Internet Explorer 7 Beta 1
Longhorn Build 5203

Contact DJDingo
Send me an email!       Send me a message with Yahoo Messenger!       Send me a message with AOL Instant Messenger!

Miscellaneous Links

Speakeasy Speed Test


Link to djdingo.com


Search Google



 

Loopback Mayhem

This started not long ago, I got into a little argument with a co-worker at work, who was trying to tell me that 127.100.0.1 is the SAME as 127.0.0.1. Now in school, we were taught that 127.0.0.1 is the internal loopback address and it basically tests your TCP/IP stack, but doesn't really do much more than that. When troubleshooting network problems, it's supposed to be the first thing you test, but it's hardly done because it's almost pointless to test for it. Anyway, this guy at work was saying that 127.100.0.1 is exactly the same as 127.0.0.1. I did a search for "127.100.0.1" on Google and got 1 result, while a search for "127.0.0.1" on Google gets about 1.2 million results. I told him they are not the same, and tried proving it to him, but we cannot ping out at work, so I decided to go home and try it first thing. I've come up with some VERY interesting results, things most people didn't know, mostly because most people never tried. Well, I did and here's what happened...

Ping tests to 127.100.0.1 in different OS's
First thing first, ping 127.100.0.1 in Windows XP. Get these results...

Windows XP results

At first my jaw dropped because I thought 127.100.0.1 was pingable, but of course it's not. Then I realized that Windows bypasses what you type and automatically puts in the loopback address of 127.0.0.1 instead. But at the summary of the test, it puts the original IP address back in there. So it looks like it's pinging 127.100.0.1, but in fact it's pinging 127.0.0.1. Windows will do this to every IP in the 127.x.x.x address range except for the network address, 127.0.0.0 and the broadcast address, 127.255.255.255, those will fail.

I thought it was a closed case, but with this weird behavior of Windows, I decided to look further, and I did the same test with other operating systems. Here's the results...

So first I tested with Red Hat Linux version 9...

Red Hat Linux results

WTF?!?! How could that be? And why in Linux? Wah??? Still perplexed, I tried other operating systems, starting with Windows 98...

Windows 98 results

WTF?!?! Windows 98 is screwy anyways, but why did this ALSO go through? Hmmm...maybe it's something with VirtualPC, that's what I was running for both Red Hat and Windows 98, so maybe that's it. So next I tried my favorite server operating system, Windows Server 2003...

Windows Server 2003 results

OK, that's more like it! Windows Server 2003 is doing the same trick as Windows XP did, that I can understand. Now here is the results of Windows Longhorn build 5048...

Windows Longhorn build 5048 results

Doesn't say much, but it says that it won't work. How about I try this in the new Windows Vista beta 1 copy?...

Windows Vista beta 1 results

Um, OK, doesn't tell much, but it DOES tell that it's not going to work. Looking good so far. My friend Jessie tries the same thing with an OS I don't currently have installed, BSD...

BSD results

Failed again. I like those results, that's what it's supposed to do! Well, six tests done and it was successful on only 2 tests, Windows 98 and Red Hat, but I'm thinking it's maybe a VirtualPC thing, I don't have those installed alone on a PC at the moment.


Conclusion
This argument with the co-worker can finally end. We are both right, or it's a draw. I was right that it cannot ping 127.100.0.1, but he was right that it's a successful command, (pings 127.0.0.1 and succeeds). So I guess we'll leave it at that. If I get other operating systems installed, I'll try them and show the screenies here.

THE END


Copyright 2005 djdingo All Rig

Copyright 2005 - 2008 djdingo.com All Rights Reserved



Today


Loopback

127.0.0.1 or 127.100.0.1 ???