mail.fulldata.com.ve has no CNAME records.
Question and response
Question
dig mail.fulldata.com.ve. NS
Answer
The response has no answer records.
Authority
fulldata.com.ve. 10793 SOA ns3.fulldata.com.ve. root.server.fulldata.com.ve. 2026022207 3600 1800 1209600 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0