ns2.six-group.com has no NS records.
NS records for this zone are defined at six-group.com.
NS records for this zone are defined at six-group.com.
Question and response
Question
dig ns2.six-group.com. NS
Answer
The response has no answer records.
Authority
six-group.com. 300 SOA a1-232.akam.net. dnsadmin.six-group.com. 2012223370 3600 360 2592000 300
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0