mail1.linphone.org has no NS records.
NS records for this zone are defined at linphone.org.
NS records for this zone are defined at linphone.org.
Question and response
Question
dig mail1.linphone.org. NS
Answer
The response has no answer records.
Authority
linphone.org. 10800 SOA ns1.gandi.net. hostmaster.gandi.net. 1774002656 10800 3600 604800 10800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0