Incremental updates limited to 120 days

[anthonyharrison]

The NVD API appears to limit the range of dates used for incremental updates to 120 days. This means that if a database has not been updated for more than 120 days, the date range will need to be divided into 120 day chunks to comply with the API limits.

[terriko]

I'm pretty certain this has been addressed alongside some other API limitations and changes that came in and out. We may want to revisit when working on #4038 -- if the api limit is still 120 days that might be good guidance for when to swap to the mirror. But I think it may be significantly less than that now.