31_3_173_081.ip.cesenanet.net has no CNAME records.
Question and response
Question
dig 31_3_173_081.ip.cesenanet.net. NS
Answer
The response has no answer records.
Authority
ip.cesenanet.net. 9471 SOA dns2.cesenanet.com. dnsadmin.cesenanet.com. 2014040611 86400 7200 2592000 172800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0