Computer has two entries in DHCP / two MAC addresses

I have a strange thing happening with one of our laptops. In DHCP it has
two distinct leases created about an hour apart, with two IP addresses
and two MAC addresses.

The ARP table for that server doesn't show any entries for that computer
at all, not either of those addresses.

In what circumstances could a computer change its MAC address by itself?
I presume that happening would be the reason why DHCP has re-registered
it with the same name but a different IP address.

Windows XP SP2 and all updates.


NZSchoolTech

You probably checked this already but I thought I'd throw it out there
anyway... Do you have both the ethernet and the wireless connected? -as each
of these has its own MAC address.

Coraleigh Miller

"NZSchoolTech" <(E-Mail Removed)> wrote in message
news:(E-Mail Removed)...
>I have a strange thing happening with one of our laptops. In DHCP it has
>two distinct leases created about an hour apart, with two IP addresses and
>two MAC addresses.
>
> The ARP table for that server doesn't show any entries for that computer
> at all, not either of those addresses.
>
> In what circumstances could a computer change its MAC address by itself? I
> presume that happening would be the reason why DHCP has re-registered it
> with the same name but a different IP address.
>
> Windows XP SP2 and all updates.

hi,
it could be more possibilites not necessary in that order :
1. another computer/device with the same name in your LAN but in a different
VLAN, behind the router etc.
2.it have a software with mac address spoofing -are plenty of that on the
net ussusally used on internet connection with MAC address counter for
billing.
3. it have another nic virtual or not (wireless, VLAN etc)
--
Dragos CAMARA
MCSA Windows 2003 server


"NZSchoolTech" wrote:

> I have a strange thing happening with one of our laptops. In DHCP it has
> two distinct leases created about an hour apart, with two IP addresses
> and two MAC addresses.
>
> The ARP table for that server doesn't show any entries for that computer
> at all, not either of those addresses.
>
> In what circumstances could a computer change its MAC address by itself?
> I presume that happening would be the reason why DHCP has re-registered
> it with the same name but a different IP address.
>
> Windows XP SP2 and all updates.
>