smtp.google.com.snk.wtf has no CNAME records.
Question and response
Question
dig smtp.google.com.snk.wtf. NS
Answer
The response has no answer records.
Authority
snk.wtf. 3600 SOA senkodns.net. admin.senko.digital. 2025051910 10800 3600 604800 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0