In short: For accounts you own or are authorised to operate, use one static address for the accounts you run and keep it, so the account’s own sign-in history stays consistent and its security alerts keep their meaning. Accounts you do not personally own need evidence of your authority over them first.
Account management here means operating accounts you own, or accounts you are contracted to run, from an address that does not change between sessions. A static ISP address is a single IP on a named internet provider’s network, reserved to you until your paid period ends. A rotating pool works the other way: each request, or each short sticky window, leaves from a new address, and that change is what this job is trying to avoid.
Sign-in checks do read the network, and some platforms document how. Microsoft’s Entra ID Protection lists risk detections for sign-ins with properties unfamiliar to the user’s history, for sign-ins from geographically distant locations in a short time, and for sign-ins from anonymous IP addresses. Most platforms publish less, but the address is one of the few signals every sign-in carries. Where access is bound to an address, the binding is explicit: Google Cloud lets you restrict an API key to specific IP addresses, and a key restricted that way is refused from anywhere else. These detections protect the account owner: a sign-in challenge, such as multi-factor authentication, is the system working, and a static address exempts nobody from it. What we say about platforms rests on documentation like this and on the way static and rotating addresses differ; we have measured no platform ourselves. The terms quoted come from our Terms of Service, Refund Policy and Acceptable Use Policy.