ns1.rainbowtel.net has no CNAME records.
Question and response
Question
dig ns1.rainbowtel.net. NS
Answer
The response has no answer records.
Authority
rainbowtel.net. 268 SOA ns1.rainbowtel.net. chrism.rainbowtel.com. 2025090377 10800 3600 604800 300
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0