What does 192 mean in an IP address?

[Felecha]

I've been unable to connect to several sites this last week. I have a home network, and my wife's machine can connect to the same sites, but my machine can't. And I've found that all of their addresses start with 192. For example:

192.233.234.20

Looks like a meaningful clue. Curiously, my router and cable modem both begin their internal IP's with 192. What's the significance of 192?

 

[Tsaico]

A long time ago some people with wiser heads than mine, set up three "classes" of ip adresses for private networks. Your 192 just signifies they are on a private network. as to why you cannot connect to them? It sounds more like you are having problems with your router or connection to it.

 

[Felecha]

What could be the problem inside one machine, that it could not reach 192's, but another machine on the same network can?

I have a cable modem connected to a Linksys 4-port router, then out to my three PC's here at home. So on my wife's machine I can reach 192.233.234.20, but can't on mine. Can't connect, can't ping successfully, can't trace. Also, our local NPR radio station has a site, a 192, and Techweb.com (great encyclopedia site) is a 192, and I can't go there either (I can't but she can). I don't know of any other 192's, but I'll bet they're all unavailable from my machine just now. This all started a week ago, with no warning that I'm aware of. I didn't change anything knowingly, didn't spill coffee on it, ...

 

[1KrazyFool]

The only private address space starting with 192 is 192.168.0.0 to 192.168.255.255. Any others are OK. As to why you are having issues, sounds like your routing tables got screwed up. Have you rebooted at all?

 

[Felecha]

What's a routing table?

I'm back home briefly, and took the time to go into Network Properties. Winipcfg was showing 255.0.0.0. Someone told me that's the problem.

I'm going to the TCP/IP for my card, selecting Properties, IP Address tab, selected Specify an address. Entered 192.168.1.102 for IP Address, which is what winipcfg shows, which I believe is the address assigned by the router. Set mask to 255.255.255.0. OK, then reboot.Came up showing 192.168.1.102, 255.255.255.0. But unable to connect to any site anywhere, not just failing at the 192's. So, back into properties, selected Obtain an IP address automatically, OK, reboot. Rebooted to a mask of 255.0.0.0 again.

My understanding is that with the router in control, it only works if I choose "Obtain automatically". So why does my wife's computer get assigned 255.255.255.0 and I get 255.0.0.0? How can I get the reset to stay that way? I've gone into the setup of the router, which I originally did when I installed it, and its settings call for a mask of 255.255.255.0. So why doesn't it stick with that for mine? I've rebooted lots of times, and reset the router with its reset button more than once. Whenever there's a short power blip ( I live out in the country and we occasionally get little blinks, some branch bends over and touches the rural power lines) I have to reset the router button, and I've always seen it restore everything OK. So what's going on now, I wonder??

 

[Felecha]

Well, well...
Turns out the silly answer was this -- winipcfg has a button right there in front of me, says "Renew". I figured there was no harm to trying, and it reset all the numbers, everything else came up what it was before, except that this time 255.255.255.0 was there, and it stayed there after a reboot. And now all the 192 sites are available. Well, well...
At least I learned some more. Not just the above, but while I was waiting for a return call from Linksys tech support (still haven't got the promised call from "one of our technicians&quot, it occurred to me that the requirement to reboot after changing Properties probably means something gets set in the registry. So I went in and searched for "subnetmask", and sure enough found the value in there set to 255.0.0.0 (ff 00 00 00, of course), so I modified it to ff ff ff 00, closed regedit, but it still didn't make the 192 sites work. And rebooting reset the registry to 255.0.0.0.
But renewing with winipcfg made everything work, and stay after reboot, and the registry setting stayed, too. So I have a little more of a sense of what this is about.
Thank you, all, for your ideas.
F

 

[Russ]

Felecha,

For future reference (in case you haven't already done it), you can log in to the router through the web interface and check all the settings. The address is 192.168.1.1 and the password is admin.

Russ, NCNE

 

[spidey07]

FYI, the 192 in the address 192.43.89.212 is the first octet in an IP address.

192 also means it is a class C address.

0-127 = CLASS A
128-191 = CLASS B
192-223 = CLASS C
224-239 = CLASS D
240-254 = CLASS E

Weird, how your mask wouldn't change. But parameters configured in the network control panel don't get overwritten with DHCP. (well sometimes they do, sometimes they don't. They're not "supposed" to according to the RFCs)

cheers!
fyi - private addresses are
10.0.0.0 - Full Class A
172.16.0.0 - 172.31.0.0 - group of class B
192.168.0.0 - 192.168.255.0 - group of class Cs (256)