We use a several year old dump of the GeoNames-DB for NER. It seems to me that the GeoName-Ids have changed since we downloaded the dump:
For example, in our dump the toponym "Blindenhorn" has the id 530072. Searching for this toponym in the current GeoNames API, we find the id 2661470.
How often are the ids changed? If we download the latest dump, how long can we be sure that the ids in our dump correspond to the online database?