pbxext.pakt.ru has no CNAME records.
Question and response
Question
dig pbxext.pakt.ru. NS
Answer
The response has no answer records.
Authority
pakt.ru. 10704 SOA adns1.pakt.ru. noc.pakt.ru. 2026022021 43200 7200 2592000 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0