_netblocks3.next-data.net has no SRV records.
Question and response
Question
dig _netblocks3.next-data.net. SRV
Answer
The response has no answer records.
Authority
next-data.net. 300 SOA dns1.next-data.net. hostmaster.next-data.net. 2025121104 14400 3600 1209600 300
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0