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DHCP keeps changing computer IP

gelat
gelat asked
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Last Modified: 2012-05-05
I have a cable connection, with 2 computers and a laptop, all getting an IP via DHCP, each with an IP of 192.168.10x (100-102)

Problem is, every now and then, during reboots, crash of time warner, etc. My IPs for each computer change. One day my desktop, wich was xx.xx.xx.101 is suddenly xx.xx.xx.100

What can I do to ensure that a particular computer keeps a certain IP?

I use WinXP Pro and a Linksys router.
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Top Expert 2013

Commented:
You can statically (manually) assign IP's, subnet mask and DNS servers to your PC's
At a command line (DOS window)  enter    ipconfig  /all
It will return those values to which your computer is currently set. Then go to  control panel | Network connections | right click on your network adapter and choose properties | highlight Internet protocol TCP/IP and click Properties and then check the appropriate boxes (circles) and enter those values. They will not change any more.
One nor you can leave everything the same except you should change the IP address. Your router has a DHCP scope/range. You don't want the possibility of a conflict by choosing something in that range, which obviously starts at 100 so choose something like 192.168.010.90-91

Commented:
Go to scope properties and make sure the duration is set to 8 days.

Or, add a reservation for each computer.  You will need the mac address for each card you want to assign the ip address to.

Jess
r2r

Commented:
Set your IP to static (manual configuration), first you get your Server IP add your gateway and DNS, write it down, then change your IP address. Each computer must have unique IP Address, and the same Gateway and DNS.

Author

Commented:
So I can leave the router at DHCP, and give each desktop a static IP within the DHCP range?
Joe RudSystems Administrator

Commented:
I would recommend IP address reservation as Jessmca mentioned.  On your DHCP server, you can set a MAC address to always receive a specific IP address.  This way your laptops are still DHCP if you need to travel, etc.

Author

Commented:
I do not know how to set a MAC address to a particular IP. How do I do this in a linksys router?
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Top Expert 2013

Commented:
Not all Linksys routers have the ability to create reservations. But if yours does it will be on the same page as where you set the DHCP scope (range) for your LAN workstations. Find the MAC address of a given computer by logging onto that computer and at a command line (DOS window) enter  
  ipconfig  /all
It will return all IP information including the "Physical address".  This is t is the MAC address, and will look something like  AA-AB-2C-12-2F-33
Then on the Linksys DHCP page for the LAN, there will be a place to enter the MAC address and the IP you wish to have assigned, every time, by DHCP.

Note: There is likely a page on your router where you can "clone the MAC address". This is not what you want. Totally irrelevant.

Author

Commented:
Ok, I have a WRTG54 1.1 Speedboost G router, and it does not have a page to assign IP by MAC
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Top Expert 2013
Commented:
You are right, WRT54G series do not offer that feature. Unfortunately it also doesn't allow you to set the Lease duration as suggested by jessmca.
You will need to assign static IP's as suggested in my first post.
.

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Commented:
I would assign static ip addresses as Rob suggests to the 2 computers and only use dhcp for the laptop.

Providing your static addresses dont clash, all three ip addresses will remain static unless anoth computer joins the mix.

Jess
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Top Expert 2013

Commented:
Thanks gelat ,
--Rob

Author

Commented:
Sorry it took so long, just got overwhelemed in work....
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Commented:
No problem. We all get swamped from time to time. It is the nature of the business.
--Rob
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