Для правильного вопроса надо знать половину ответа
$ dig +trace www.teacher-office.cf
...
www.teacher-office.cf. 0 IN CNAME teacher-office.cf.
teacher-office.cf. 300 IN A 195.20.53.45
cf. 10800 IN NS a.ns.cf.
cf. 10800 IN NS b.ns.cf.
cf. 10800 IN NS c.ns.cf.
cf. 10800 IN NS d.ns.cf.
