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When is a dynamic IP address assigned?

I just want to know WHEN my ADSL router will assign my machine an IP
address? Is it as soon as Win 7 gets to the login screen or is it done at power
on? It’s not a static IP address; it just assigns the next available one that’s
not in use. Thanks a lot!

In this excerpt from
Answercast #67
, I look at the timing involved when a computer assigns an IP
address.

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When is an IP address assigned

It varies. It’s actually, typically part of the boot sequence – but exactly
where is kind of difficult to say.

Your machine definitely has an IP address before you login to it because you
could login to it remotely. So by definition, if you can log into it
remotely with something like Remote Desktop, it has an IP address – and that
had to happen before you logged in at the console.

The best I can say really is that somewhere between the time you begin the
boot and the login screen appears, somewhere in there it should get an IP
address.

“It depends”

Now, here’s the problem (and here’s why I even have to be squishy on that); if you login quickly, it’s possible that you may not have an IP address
yet. We often see this with wireless networks, which for whatever reason can
take some more time to connect than other networks and therefore can take more
time to make that request for an IP address.

So in reality, what’s going on here is the process to request an IP address,
to request the assignment of an IP address, or the process to enable and turn
on the network adapter and do all that, begins sometime while you’re booting.
It takes however long it takes (usually it’s pretty quick; sometimes it can be
a little bit long), but it runs in parallel then to whatever else is happening
on the screen.

So, the login screen may come up, you may have an IP address at
that point; you probably will have an IP address pretty soon thereafter. If you
login quickly,… well, it’s possible that you may login to a machine that hasn’t
really reached that “I’ve got an IP address” point yet.

But that’s really all it is. It’s happening at some part of the boot
process. It’s independent of when you login. It’s just that sometimes it takes
a little longer than others.

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