Okay, sync completed. Hopefully this issue should be resolved.
In the future, if one of you has a intermittent DNS issue and is technically inclined, try installing dig in a UNIX environment and compare the results of:
dig @ns1.heliohost.org yourdomain.com
dig @ns2.heliohost.org yourdomain.com
If the results are different (especially if one of the results does not exist), then we have a problem.