ns11.ervers.com has no CNAME records.
Question and response
Question
dig ns11.ervers.com. NS
Answer
The response has no answer records.
Authority
ervers.com. 10800 SOA ns11.ervers.com. admin.ervers.com. 2026022504 28800 7200 604800 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0