rev.hosting.nbs-system.com has no SRV records.
Question and response
Question
dig rev.hosting.nbs-system.com. SRV
Answer
The response has no answer records.
Authority
rev.hosting.nbs-system.com. 86400 SOA ns0.nbs-system.com. root.nbs-system.com. 2015070901 6000 7200 2419200 604800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0