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DHCP - Dynamic Host Configuration Protocol
Or how your computers get their networking settings automatically. How does
this work? And why does it sometimes not work?
In your computers on a network there is a TCP/IP Network setting for how you
get your network settings for that computer (and that specific network
connection, if you have more than one connection). Usually this setting is
something like "Obtain IP Address Automatically" and "Obtain DNS Server
Automatically". Most people don't realize it but the "Automatic" setting means
for the computer to contact a DHCP Server on the network to obtain the IP
Address, Network Gateway, and DNS Server settings.
So where is this DHCP Server?
The DHCP Server is usually in whatever is your network gateway (Default Gateway)
which is usually the router that gets you onto the Internet. For those that
share a connection from Microsoft Windows that server is in that Windows box.
So how does it work?
When you connect to your network either by plugging into a wired connection or
connecting wirelessly to a wireless network, your computer immediately seeks
out a DHCP Server to obtain its settings.
The Protocol dialog looks something like this:
When your computer runs through this procedure of obtaining an IP Address and
network settings it is usually successful and very quickly completed. If it
fails in this procedure it will usually pop up a dialog box and tell you that
it failed. You should know another indicator of DHCP failing, that is your
computer assigning itself and IP Address in the range: 169.254.x.x. If you
see that 169.254 instead of and Internet IP address (or an IP from your router
such as 192.168.x.x) then you can bet DHCP failed and you will have no network
or Internet functioning at all. Windows often tells you "Limited Connectivity".
So what are some reasons why it would not be working?
First of all there should not be more that one DHCP Server on a network. So it's
important to make sure that there are not two Internet Sharing PC or Router
boxes on the network.
Also many after-market firewall softwares wreak havoc on DHCP and Connection
Sharing. I can't tell you how many times I've had to un-install Norton Internet
Security or other Anti-Virus packages that include firewall functionality.
What are these companies thinking anyway??? You can't block DHCP or DNS
out-of-the box in the default configuration companies!!! That should not be an
after-thought in a products testing. People need to go on and share the Internet
connection. You want your product returned go ahead and block this stuff. I'll
keep un-installing your software.
You're connection didn't really connect. In Windows the wireless key codes
often get corrupted somehow. The only way to fix that is to clear the Preferred
List of Wireless Connections. Remove your network from that list and connect
again. You will be required to re-enter your wireless key code or pass phrase.
WiFi Hotspot Connections assign your IP Address by DHCP also. Sometimes you
will connect to a hotspot and get an IP Address assignment but the Internet
will not work. That's probably because the hotspot doesn't have the Internet
connection on at the time. This usually doesn't happen with true public
hotspots, but does happen with home or office network connections. If you
connect to the Linksys or Hpsetup or Netgear or Dlink (manufacturers names)
networks then you can bet it's someones "private" network. Just because they
neglected to turn on Security doesn't change the fact that it is a "private"
network. And you can't complain that they didn't leave the Internet on for you.
You can check what your ip address is, and the gateway. See if you can ping the
gateway? Then see if you can ping an Internet Web Site like www.google.com.
[That's all for now. If you have any questions on this please contact me.]
Please contact us for information or for a quote: Telephone Numbers
are: 954-683-3426 mobile, or 954-977-5245.
