primary.maxnameserver.net has no SRV records.
Question and response
Question
dig primary.maxnameserver.net. SRV
Answer
The response has no answer records.
Authority
maxnameserver.net. 900 SOA dns.dns1.de. hostmaster.internetwire.de. 2019070301 900 7200 604800 900
Additional
. 0 OPT ; payload 1680, xrcode 0, version 0, flags 0