cURL error 6: Could not resolve host: XYZ.revelup.com.revelup.com (see http://curl.haxx.se/libcurl/c/libcurl-errors.html)
Thus usually means you have put the full Revel up URL in the authorization settings you only need to put in the first part - In the above example you should put XYZ.
To Change in your DSYNC dashboard simply click on your Revel container
then settings then authorizations. Then only put in the first bit of the revel url