mail03.postel.sk has no NS records.
NS records for this zone are defined at postel.sk.
NS records for this zone are defined at postel.sk.
Question and response
Question
dig mail03.postel.sk. NS
Answer
The response has no answer records.
Authority
postel.sk. 86400 SOA auth1.ns.swan.sk. hostmaster.swan.sk. 2011052601 86400 7200 604800 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0