Generally, the idea is that each system release have a new moduli file.

The 1024-bit moduli (most commonly used) should be replaced regularly,
probably on the order of every year, but could be needed more often. 
Perry Metzger claimed there was going to be an analysis paper on it,
but I've not seen it.

About 15 months ago, I submitted a replacement
  http://www.netbsd.org/cgi-bin/query-pr-single.pl?number=23076

OpenSSH replaced theirs 12 months ago (currently 1.2).

NetBSD has not updated from OpenSSH (still using one going on 5 years
old), nor used those I specially generated for you.

I'd be willing to guess that you've shipped 2.0 with moduli that have
long since been cracked by most major governments, and possibly major
corporations.  Why?

-- 
William Allen Simpson
    Key fingerprint =  17 40 5E 67 15 6F 31 26  DD 0D B9 9B 6A 15 2C 32