pool.ntp.org has no NS records.
NS records for this zone are defined at ntp.org.
NS records for this zone are defined at ntp.org.
Question and response
Question
dig pool.ntp.org. NS
Answer
The response has no answer records.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0