The entire world now talks to itself using Transmission Control Protocol/Internet Protocol, usually abbreviated to TCP/IP. Back in the distant past other protocols were used, NETBUEI, DECNET, and such. They are all dead now, and TCP/IP rules. Protocol is a set of rules for doing business. For instance protocol for using the plain old telephone goes like this. Lift handset. Dial 1 plus the area code for long distance, otherwise dial just seven digits. TCP/IP, since it is used by computers is more complex, but it deals with the same issues.
Part of TCP/IP is
the IP address, a long string of digits that works like a telephone
number. Each computer has to have an IP
address, and all the IP addresses must be unique. Two computers may NOT have the same IP
address, for obvious reasons. In the old
days, you typed the IP address into your computer. The network administrator for your site gave
out IP addresses, kept track of the ones in use, and reissued IP addresses used
by old computers that were taken out of service. As you can imagine, the Network Administrator’s
job got harder and harder to do in outfits that might have thousands of desktop
PC’s on the Internet.
So they invented an
automatic program running on the server, to take care of it. Each time a desktop powers up, it asks
the TCP/IP server to give it a new IP address, which it keeps until it
powers down. This server program is
called Domain Name Server (DNS) or Dynamic Host Control Protocol (DHCP). Since
Windows XP goes back to the bad old days of typing in IP addresses by hand, it
still supports that, as well as DNS/DHCP.
You, proud computer operator get the choice of which, or both, to use.
Normally all this
complexity just works, and your computer goes on line every time you power it
up. But sometimes, for obscure and
undocumented reasons, DNS fails, your
computer does not get an IP address, and you get a little message down on the
task bar about “limited or no connectivity” and “IP address” .
What to do?
Windows Repair
Built into Windows is a repair program. It will reset the hardware by powering it
down and then up again, and then go thru the “ask-the-server-for-an-IP-address”
song and dance again. This works a good
deal of the time, (but not always). To
start repair, left click on the channel’s icon down on the task bar. This will open up a “status” window that will
tell you what’s broke and offer more information tab. Click and you will find another tab labeled
“Repair”. Click on it and hope. It may take a while, it gives the server
plenty of time to get its act together and issue an IP address. If it doesn’t work, you will have to wait
about a minute to get the bad news. If
it does work, you are home free, at least for today.
IPCONFIG
This is essentially a
manual way of doing what Repair does, with some benefits of extra
information. IPCONFIG is a DOS program,
you launch it from the DOS window. Get the DOS window open from the Windows Run
option on the Start menu. Microsoft
renamed DOS to CMD, for the Run option. That helped everyone, a lot. Thanks MS.
Like all DOS
programs, IPCONFIG works off switches on its command line. Switch /ALL makes it list out all the I/O
channels (Ethernet, Wireless, etc) on your machine. It gives the IP address (if it has one), serial numbers, and other stuff. Switch /RELEASE hangs up your internet
connection, turns in your IP address, and takes you off line. Switch /RENEW
does the “ask-the-server-for-an-IP-address” song and dance. I don’t know what IPCONFIG does with no
command line switches, so I don’t run it that way. Doing IPCONFIG /RELEASE followed by IPCONFIG /RENEW is equivalent to
doing the Windows Repair.
Alternate Configuration
And, sometimes the
server is feeling cranky and just won’t issue an IP address no matter what. My “server” is a little 4 port Belkin wireless
router, it works fine on Trusty Desktop, but just won’t issue an IP address to
AntiqueLaptop.
You can configure
the channel ask for an IP address, but if that doesn’t work, just use an IP address that you
assign. And this works on the Belkin
router, why I don’t know. To set this
up, left click on the taskbar icon of your channel. Get the status window. Click on “Properties” lower left.
This will display a list of all the drivers, protocols, and other bits
of software that make the channel work.
Scroll thru the list and find “TCP/IP”
Click on the properties button that comes up with the selection of
TCP/IP. This accesses the properties of
the TCP/IP software. On the “General”
page of TCP/IP properties, you want to check
“Obtain an IP address automatically” and “Obtain a DNS Server address
automatically”. That will make your computer attempt to do the DNS song and
dance. If that dance should fail, it
goes to Plan B, “Alternate Configuration”.
Check “User Configured”. The
other choice “Automatic Private IP address” is undocumented, but I believe it
only works in XP Professional, which few of us have. Below the “User Configured” are boxes for IP
address, sub net mask, Default Gateway,
and Preferred DNS server. Fill them in.
What to Use? For my Belkin router 192.168.2.4 works for IP
Address. Trusty Desktop, who gets his IP
address from DNS (the router) is 192.168.2.2.
And he is the only other computer in the house, so I figured the .4 IP address
ought to work and not conflict. If you
have a different router, different IP addresses might work. You gotta do some snooping around. Sub net mask is 255,255,255,0. Both Default Gateway AND Preferred DNS Server is 192.168.2.1, again I
got that from Trusty Desktop.
And, Lo and Behold, Antique Laptop is now back on the
net.
