a0.rackcdn.com has no NS records.
NS records for this zone are defined at rackcdn.com.
NS records for this zone are defined at rackcdn.com.
Question and response
Question
dig a2.dscg10.akamai.net. NS
Answer
The response has no answer records.
Authority
dscg10.akamai.net. 1000 SOA n0dscg10.akamai.net. hostmaster.akamai.com. 1772957706 1000 1000 1000 1800
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0