It is from story 1 to comment/story 10,002,378 :-)

The archive is 1.12GB big and contains 1 JSON document / per line. The JSON document is approximately the format returned by the official HN API (although there are some exceptions since some of the comments are not available through the official API and those had to be retrieved through the Algolia API and/or scraped from the site).

Also, about the date range: from October 10, 2006 until yesterday (when HN hit ~10m comments / stories).