Persistent Inconsistencies in IP Geolocation Data for 'What is My ISP?' Tool After Database Switch

Our "What is My ISP?" web tool recently transitioned from our long-standing IP geolocation database provider to a new, supposedly more robust, alternative to enhance our IP data accuracy and coverage. Post-migration, we're encountering persistent and significant inconsistencies in the IP Geolocation data, specifically concerning ISP identification and associated geographical details. Certain IP ranges, particularly those belonging to mobile networks and various VPN services, are now frequently misidentified or show vastly different results compared to our previous provider and other reputable public lookup services.

We've thoroughly reviewed API integration and parsing logic to ensure correct data extraction and mapping from the new provider. We also implemented aggressive caching invalidation and reduced Time-To-Live (TTL) settings to rule out data staleness issues. Furthermore, we cross-referenced problematic IPs manually against several well-known third-party IP lookup tools (e.g., IP-API, WhatIsMyIP.com) and found our new data often diverges significantly. We even performed sanity checks on server-side network configurations and DNS resolution to ensure no external factors are skewing results.

Specifically, IPs that were reliably identified as major mobile carriers (e.g., T-Mobile, Verizon) by the old database are now frequently reported as generic data centers, residential ISPs, or even completely different countries. These discrepancies extend beyond just ISP names, affecting city, region, and sometimes even country-level IP Geolocation for a non-trivial percentage of lookups.

We've considered that the new provider might have weaker coverage for specific regions or types of IP allocations (e.g., mobile subnetworks), but we're struggling to pinpoint the exact technical reason or a robust validation methodology to confirm this without extensive, manual dataset comparisons. We're also unsure if there's a more advanced integration pattern we're missing for handling potential data conflicts or quality variations between providers.

Therefore, we're keenly seeking expert advice on advanced validation strategies for IP Geolocation database accuracy beyond simple cross-referencing. We're also interested in techniques for intelligently merging or prioritizing IP Geolocation data from multiple providers to achieve higher confidence. Finally, any insights into common, but often overlooked, technical pitfalls when integrating new IP data services that could lead to such widespread inconsistencies would be invaluable. Waiting for an expert reply.