DHCP assigning address outside of Scope

[Mr Davo]

Hi Everyone,

I have a strange networking situation. Let me start by saying this situation is on a Domain, and that I am using Windows 2011 SBS and Windows 7 clients.

My server has a DHCP range of 192.x.x.150 to 192.x.x.199 - and all other I.P. addresses are static.

On a workstation located at I.P. 192.x.x.13 I am seeing an address conflict.

When I perform an "nbtstat -a 192.x.x.13" command from the server I am given the logical computer name of a staff members personal laptop.

Investigation of the laptop reveals that it is set to DHCP, and clearly the address of 192.x.x.13 is outside of my servers DHCP scope, so this I.P. should never be assigned, let alone in duplicate.

I Googled this topic before posting, and it was suggested that IPv6 could be having an adverse affect. I determined this because I performed a ping on the laptop and only got a MAC address back rather than an I.P. address.

However after unticking IPv6, and rebooting, the laptop is still causing havoc.

I can set a static I.P. address on the laptop, however this is not ideal.

If anybody knows of any way that I can stop this from happening it will be greatly appreciated.

Kind Regards,

Davo

 

[Mr Davo]

Hi Everyone,

Further to my earlier post here is a screen shot of both ipconfig & Control Panel settings on the Laptop:

I have actually managed to fix this by -

1). Changing the IPv4 settings to static - and assigning the address in question (e.g.192.x.x.13)
2). Subsequently changing the IPv4 settings back to "Obtain an IP address automatically"

The laptop now reports an I.P. address of 192.x.x.174 (Preferred), which is actually within the DHCP scope of my Server!

I have actually managed to fix this by -

1). Changing the IPv4 settings to static - and assigning the address in question (e.g. 192.x.x.13)
2). Subsequently changing the IPv4 settings back to "Obtain an IP address automatically"

The laptop now reports an I.P. address of 192.x.x.174 (Preferred), which is actually within the DHCP scope of my Server!

Last week my Server decided to reset the DHCP scope to 192.x.x.1 to 192.x.x.255 (with a few "address excludes" added for good measure), I believe the reset resulted from Windows updates, so I am going to assume that this issue was a left over from last weeks "undiscussed" change!

Kind Regards,

Davo