do ISPs keep track of end-user IP changes within thier network?

Ray Wong rayw at
Thu Dec 12 08:49:45 UTC 2013

been a while, but seems like lately it's more a question of how long. ISPs
can be in position where they need to, but as things have consolidated,
seems like they'd really like to forget it as soon as they can. If you've
got a specific case in mind, likely best to find a direct contact and get a
response about policy, even if it has to be off-record. The big ones (like
one I likely shouldn't mention by name unless they do as I don't work for
them) definitely do, at least long enough to handle DMCA requests and other
legal obligations.


On Wed, Dec 11, 2013 at 9:36 PM, Mikael Abrahamsson <swmike at>wrote:

> On Wed, 11 Dec 2013, Carlos Kamtha wrote:
>  just a general curiousity question. it's been a long time since ive
>> worked at an ISP.
>> back then it was non-expiring DHCP leases and in some cases static IP for
>> all.. (yes it was long ago..)
>> Any feedback would be greatly appreciated..
> Yes, it's very common to keep track of what user account/line had what IP
> at what time.
> --
> Mikael Abrahamsson    email: swmike at

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