mx01.1and1.com has no NS records.
NS records for this zone are defined at 1and1.com.
NS records for this zone are defined at 1and1.com.
Question and response
Question
dig mx01.1and1.com. NS
Answer
The response has no answer records.
Authority
1and1.com. 600 SOA ns-1and1.ui-dns.com. dnsadmin.1und1.de. 2013096354 10800 3600 604800 600
Additional
. 0 OPT ; payload 1220, xrcode 0, version 0, flags 0