Dynamic IPs... fixed cities?

Hey there
Love the site/API (however still limited for Europe)!
But... what with dynamical IPs?
Are they always in the same city? Or is it possible that today my IP is in "CITY A", and tomorrow that IP is in "CITY B" (at about 10 miles from A) ?
Because that's why I don't understand why people would submit their city, if the next day, it might be somewhere else...
I'm no network connaisseur, but I don't know how those /24 block are assigned
Let me know!!
Love the site/API (however still limited for Europe)!
But... what with dynamical IPs?
Are they always in the same city? Or is it possible that today my IP is in "CITY A", and tomorrow that IP is in "CITY B" (at about 10 miles from A) ?
Because that's why I don't understand why people would submit their city, if the next day, it might be somewhere else...
I'm no network connaisseur, but I don't know how those /24 block are assigned

Let me know!!