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Summary: If there is a conflict with your IP address, it could result in only one of the machines on your network working at a time.
I suspect pretty much what you've indicated: a problem in the IP address assignment. But exactly what problem depends on a few details. Details we can look at. • First, let's make sure that the "hub/router" is in fact a router. That's important because most ISPs (and, notoriously, most all cable ISPs) will give you one and only one IP address. If you just put in a hub, then both computers are competing for the single address. Typically the first one to request the IP address will win and be able to work. The solution there is to get a router. A broadband router will take the single IP address for itself, and then hand out multiple local IP addresses to all the computers connected to it. It'll do some magic (called NAT, for Network Address Translation) to make sure each computer's conversations on the internet are kept straight. Another side effect of using a NAT router is that you are very effectively firewalled and protected from several different internet threats. So let's say you have a router, or your ISP will hand out multiple IP addresses. Or both. Let's examine what your machines are seeing. I'll assume Windows XP at this point, but much of this applies to WIndows 2000 and Windows NT, and there are equivalent steps for Windows 9x. Open a command prompt, and type "ipconfig /all", followed by Enter. You should see something very much like this:
Windows IP Configuration
Host Name . . . . . . . . . . . . : AskLeo
Primary Dns Suffix . . . . . . . :
Node Type . . . . . . . . . . . . : Mixed
IP Routing Enabled. . . . . . . . : No
WINS Proxy Enabled. . . . . . . . : No
Ethernet adapter Local Area Connection:
Connection-specific DNS Suffix . :
Description . . . . . . . . . . . : 3Com 3C918 Integrated Fast Ethernet Controller (3C905B-TX Compatible)
Physical Address. . . . . . . . . : 00-C0-4F-79-84-6A
Dhcp Enabled. . . . . . . . . . . : Yes
Autoconfiguration Enabled . . . . : Yes
IP Address. . . . . . . . . . . . : 192.168.1.104
Subnet Mask . . . . . . . . . . . : 255.255.255.0
Default Gateway . . . . . . . . . : 192.168.1.1
DHCP Server . . . . . . . . . . . : 192.168.1.1
DNS Servers . . . . . . . . . . . : 206.124.128.1
206.124.128.3
Lease Obtained. . . . . . . . . . : Tuesday, July 13, 2004 6:19:55 PM
Lease Expires . . . . . . . . . . : Wednesday, July 14, 2004 6:19:55 PM
We're first going to look at the IP address assigned. This listing, from my own machine, shows an IP address beginning with 192. That's one of the address ranges reserved for private networks. Along with "Dhcp Enabled" being "Yes", this implies that I'm behind a router, and that the router has assigned me my IP address. If instead you see "0.0.0.0" or an address that begins with "169.", then Windows was unable to get an IP address. "0.0.0.0" is no IP address, and a "169." is an address that Windows will simply make up in order to have an address - but most things won't work. If you're behind a router and you don't get an IP address, then you need to confirm your physical connection, and more likely your router's configuration. DHCP, the IP-assignment protocol, can be turned off on routers; make sure it's on. If one of your machines get an internet address beginning with something other than 192 or 169, say "156." instead, and the second machine fails to get an IP address at all, then I'd bet that the first machine is connected directly to the internet, and that router either isn't a router at all, or its DHCP has been turned off. An interesting test is to go to both machines and note the IP addresses they're using. On the machine that can't connect to the internet, in the Command Prompt, type "ping " followed by the IP address of the working machine. Chances are that will work, and indicates that the physical connections are all working. In fact there's even a good chance that pinging in the other direction, from good to bad, will work if the failing machine has had a 169. address assigned to it. Related:
Article 380 | Posted July 13, 2004 |
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Hi, My laptop is assigned DHCP ip in office and i use static ip at home for internet. In office my outlook and internet both are working fine. But i am not able to connect to other file server. I don't know why? although all the server ping from my system. Can you help me out?
Posted by: Sanjay Gupta at January 4, 2007 02:31 AMI think this MS article addresses that: http://support.microsoft.com/default.aspx?scid=kb;en-us;283676&sd=tech
Posted by: Leo Notenboom at January 4, 2007 09:44 AMI have a LAN connection, and I use it in my desktop computer. When i plug lan cable in my laptop, internet does not run. How can i run it on my laptop also?
Posted by: Lokesh at February 10, 2007 01:41 AMthanxxxx
I have the following probleme with my PC.
Posted by: cata at March 18, 2007 09:22 AMI have a PC with a wireless card.
I can connect to a wireless network but sometimes I did not receive any IP or I receive an IP ho starts with 169.At the same wireless network I can conect any time with a laptop and I do not have any probleme with the IP.
Please , tell me haw do I resolve the probleme
My mail is [Email Address Removed]
I wait for anserws
thak you
THX
Posted by: Jorge at April 10, 2007 01:42 PMI need to clarify something about IP's and speed vs. bandwidth.
A single computer will only get one IP no matter how many you subscribe to, and therefore no matter how many IP's you have a single computer will NOT get any speed increase.
To use multiple IP's, you need to use a switch-- a hub might work but trust me here and just pay the extra few dollars for a switch. If you know how to configure it properly, a router can do the same thing, but it means disabling the router functions so it will basically operate like a switch (only it costs a lot more).
Each device connected to the switch will draw a different IP (as long as you subscribe to enough IPs, of course). Most ISP's limit your bandwidth by IP, so you might be able to get FULL bandwidth to EACH computer using this method.. up to the physical limit of the modem of course.
This means that in many cases if your ISP says they give you 7meg down and 256k up, having two computers each with it's own IP will usually give you the 7meg down 256k up on EACH machine, but NOT double the bandwidth on either one.
The easiest way to test if your ISP limits you by IP or by total bandwidth across the modem is to hook 2 comps up to a switch, and run an upload speedtest on each computer seperately, note the results, then run the test again on both computers at the same time to compare the difference.
Posted by: EriktheTech at May 26, 2007 10:27 PMI have an ISP that cliams they must charge extra for using more then one PC. If I connect a s/w both pc get an IP. which I assume they will charge for if I stayed connected, But if I use a NAT router why would they care 256k is 256k that is all the router will get with DHCP connection and a IP provided to it. Will they look past the router to the internal IP's and charge me for spliting the bandwith I already pay for.?? Thanks
Posted by: Kyle at June 26, 2007 11:45 PM-----BEGIN PGP SIGNED MESSAGE-----
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It's possible to tell, but only if they monitor your traffic and look for
random clues like machine names in email headers. Depends on how intrusive they
want to be. They will be able to tell that you have a router pretty easily
though. Personally, when I was in your situation I used a router and things
were fine.
Thanks,
Leo
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Posted by: Leo A. Notenboom at June 27, 2007 03:49 PMKrbU+u+JauG9gEpFSto8T/k=
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When I run the "ipconfig /all" command, it will open for a second and then disappear! Why is this happening????
I'm trying to solve a problem with my laptop losing its internet every 5-7 days or so. I just can't understand what is causing this to happen! I thought I'd check out what you suggested but the "ipconfig /all" window won't stay open!
Thanks,
Posted by: Gina at July 22, 2007 06:57 AMGina
When I run the "ipconfig /all" command, it will open for a second and then disappear! Why is this happening????
I'm trying to solve a problem with my laptop losing its internet every 5-7 days or so. I just can't understand what is causing this to happen! I thought I'd check out what you suggested but the "ipconfig /all" window won't stay open!
Thanks,
Gina
This is for Gina and others who go to RUN and type in the IPCONFIG command. I was having the same problem ipconfig would open a window for a second - then close. I went thru start, all programs, accessories, command prompt and it worked fine:).
Posted by: Charlotte Hyatt at August 1, 2007 09:21 PM