pop.cebhead.com has no NS records.
NS records for this zone are defined at cebhead.com.
NS records for this zone are defined at cebhead.com.
Question and response
Question
dig pop.cebhead.com. NS
Answer
The response has no answer records.
Authority
cebhead.com. 3601 SOA dns1.registrar-servers.com. hostmaster.registrar-servers.com. 1770497067 43200 3600 604800 3601
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0