NS1.VPLS.NET has no CNAME records.
Question and response
Question
dig NS1.VPLS.NET. NS
Answer
The response has no answer records.
Authority
VPLS.NET. 2997 SOA ns1.VPLS.NET. hostmaster.VPLS.NET. 2026021900 3600 7200 1209600 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0