Recently I wrote about an issue I encountered where a client's website was missing its GeoIP data (and the related back-end analytics data) entirely. While the changes discussed in that post solved the problem of there being no MongoDB data for GeoIP lookups at all, I continued to see odd issues with many users not being located after those fixes were made. Sorting this out seems to suggest that some of the "common wisdom" about configuring GeoIP for analytics isn't right – so here are my latest findings: