That is a very good question. Now, geofeed does not have a verification system. Active measurement is something we use to verify ASN or ISP itself.

Even active measurement has its own limitations. Now in those case where we see active measurements not producing reliable data, we do reach out to ISPs and ASNs to purchase a server in their facility. Geofeed as a system is voluntary and most major ISPs actually do not maintain or even publish that. For example, today I found out a major UK-based telecom geolocated 500k IP addresses in a town with 200k people. ISPs are not inherently incentivized to maintain the accuracy of their self-reported, voluntarily published location data. So, we do proactive outreach to purchase a server from them so we can provide consistent accurate data for their IP addresses.

On the matter of advertised locations not matching actual location, I highly recommend reading this: https://ipinfo.io/blog/vpn-location-mismatch-report

For residential ISPs, we do a lot of outreach and open communication to build a good partnership with them. The goal is that we pay for the privilege to report accurate data for them.

> How often does your active measurement data disagree with geofeed data?

Very frequently.

Here is the summary peer reviewed research paper on this matter: https://community.ipinfo.io/t/ip-geolocation-and-geofeeds-wh...

Active Measurement (1,330 probes, 27.7M RTTs):

  - Country-level: 92.0% accurate → 8% wrong country
  - City-level: 79.6% accurate → 20.4% wrong city

  - Country-level: 84.5% accurate
  - City-level: 29.9% accurate → 70% wrong city

Primarily through active measurement, we are also running a lot of research around more reliable mobile geolocation data.

Because our data is updated daily, I think due to the refresh rate we have an accuracy advantage.

> If I am troubleshooting a support case that is days/weeks/months old, wouldn't this mean that enriching this information at a later date may give me different data than what it was associated with at the time the requests were made? My understanding was that IPs get re-assigned.

You will be surprised to know that historical IP location does not have much demand.

If you are evaluating a support case after some time, you should work with your current data. If the customer raises a question, you address this in real time with their current IP address.

Usually, I do not recommend storing historic IP geolocation information. In most operations, the enrichment happens in real time within the day. Unless you want to do periodic reporting of some sort.

Internally, we of course have the data, but because our IP geolocation is so accurate, it currently sits at around 700 MB. If you add a historical layer to that data, it will be a terabyte of data. There is not much consumer need for it.

> How frequently do IP-to-location mappings change in practice?

https://ipinfo.io/blog/how-many-ips-change-geolocation-over-...

On the city level is 1.3% each day and 16% each month.

> Do you offer historical IP data snapshots?

I highly recommend that you work with current day's data.

In cases where we provide historical data, it is usually for academic research.

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Let me know if you have any more questions.