Zimbra installation error

hello
please why is it that after installing zimbra on centos 7 from Contabo the zimbra won’t install ssl because it’ll show error about A record and AAA record also it won’t deliver email and also when i check my domain on whoer.net it shows couldn’t find hostname

my second question is what is the different between zimbra and pmta 5.0 with ssl… which of them is more powerful