DHCP assigning wrong IP address

Question

Level 1

0 points

DHCP assigning wrong IP address

We have recently started to have problems on our home networks. I take my MacBook Pro back and forth between two houses both of which have routers about 3 months old.

My MBP is set to use DHCP on the built-in AirPort to assign an IP address but it assigns an address like 169.254.111.112 when it should be assigning a number like 192.168.1.106. If I click "Renew DHCP Lease" a few times it usually gets a correct IP address.

The weird thing is that when it has the wrong IP address it can still access the internet. Sites like eBay load but I can not sign in. Nationalcity.com does not load at all and amazon.com is the same as eBay.

If I try to open limewire, transmission, Apple Remote Desktop, Yahoo widgets, and almost every other application that needs to use the internet. The iTunes store works just fine but I think that's because it uses port 8080.

My problem is in the third paragarph. How do I get my MBP to obtain the correct IP address. I can't use "Using DHCP with manual address" beacuse I take it back and forth between two houses and routers. And that doesn't fix it anyways.

Thanks for any help!

EDIT:
When the computer gets the IP address 169.245.111.112 the AirPort status reads "Self-assigned IP"
When the computer gets the IP address 192.168.1.106 the AirPort status reads "Connected"
I don't know what this means but it looks important.

Message was edited by: Callforhelp

17" MacBook Pro | 8 Core MacPro | 30" Cinema Display, Mac OS X (10.5.6)

Posted on Mar 31, 2009 11:12 PM

Reply

Answer 1

dbsneddon

Level 4

1,542 points

Apr 1, 2009 12:01 AM in response to Callforhelp

This doesn't explain what is going on but, any reason you cannot create two
different locations with fixed IP addresses then just select the relevant location?
Personally, I don't use DHCP on any of my machines neither do I use AirPort.

Dave

Reply

Answer 2

Apr 1, 2009 1:07 AM in response to Callforhelp

My MBP is set to use DHCP on the built-in AirPort to assign an IP address

In fact the MBP 'obtains', not 'assigns' the IP number, but 'Use DHCP' is indeed the correct setting.

When the computer gets the IP address 169.245.111.112 the AirPort status reads "Self-assigned IP"

This means the computer has failed to obtain an IP address from the router, and has assigned an emergency one itself: this prevents connection to the internet. You may be seeing cached pages, which of course you can't reload or sign into.

When the computer gets the IP address 192.168.1.106 the AirPort status reads "Connected"

This is a correctly assigned IP number.

Why you are failing to get an IP number in the first place I can't say. The router must be set to 'use DHCP' or equivalent. Make sure that the computer is not attempting to connect to some other network - if your neighbour has a wireless network it might be attempting to connect to that.

Reply

Answer 3

Dogcow-Moof

Level 8

36,833 points

Apr 1, 2009 6:08 PM in response to Roger Wilmut1

Roger Wilmut1 wrote:
This means the computer has failed to obtain an IP address from the router, and has assigned an emergency one itself: this prevents connection to the internet. You may be seeing cached pages, which of course you can't reload or sign into.

"Emergency one" is a bit incorrect here.

It means the computer has assigned itself an IP address, as it was unable to obtain one from the network's DHCP server.

This system works quite well to connect two systems to each other, as an example.

Reply

Answer 4

Callforhelp Author

Level 1

0 points

Apr 1, 2009 7:45 PM in response to Callforhelp

How do I get my router to assign the correct IP address? Or how do I setup more than one location?

Reply

Answer 5

dbsneddon

Level 4

1,542 points

Apr 1, 2009 8:11 PM in response to Callforhelp

To create a location goto System Preferences > Network and the location will be displayed
at the top of the pane (probably Automatic in your case). Click on the arrow to the right
of the name and then select add location. Create a location for House1 and configure that
with a fixed IP address then create a location for House2 and configure that location.
To get the default gateway, subnet mask and dns details, initially use dhcp then make a
note of the relevant details to use when you do the manual configuration.
Might sound like a hassle but I never use dhcp and have multiple locations defined with
fixed addresses and never have any problems - just select the location and away you go.

Dave

Reply