Since the DNR calls all execute asynchronously you do not get the
results back immediately. Instead, you get a dnr result object. You
can check this object to see whether the query is complete, and access
its attributes to obtain the information when it is.
Alternatively, you can also reference the result attributes directly,
this will result in an implicit wait for the query to complete.
The rtnCode and cname attributes are always
available, the others depend on the type of query (address, hinfo or
mx).