auth20-wcom.uu.net has no CNAME records.
Question and response
Question
dig auth20-wcom.uu.net. NS
Answer
The response has no answer records.
Authority
uu.net. 2638 SOA AUTH00.NS.UU.NET. hostmaster.UU.NET. 100019035 3600 900 604800 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0