I found out that when you create a 'A' record it does not warn you about the trailling dot. If the dot is not there, MyDNS will not show the entry in replyes.
I guess you mean when the A Record is a FQDN and not that short version in the BIND9 config with the @ for "autocompletion"?
When you put in a SOA record, for example : ' mydomain.tld ' it warn you that you must put a trailling dot : ' mydomain.tld. '. But when you create a 'A' record (or mx\cname) for example A: ' mydoamin.tld ' CNAME: ' www.mydomain.tld ' it allow you to put them in without the trailling dot, like in my example, while the dot is mandatory for MyDNS to resolve correctly.
As far as I remember, A-Records without a dot are fine. If you add "mydoamin.tld" as A-Record to the SOA "mydoamin.tld" it results in the domain "mydoamin.tld.mydoamin.tld" which is a valid domain name but maybe not that what you wanted. But if you add "www" as A-Record to the SOA "mydoamin.tld" it results in "www.mydoamin.tld" which is a common domain name
Got it now... Still, since on probably most systems there will be a 'A' record with only the domain name, maybe there is a place to put some warning about the subject (or at least document it).
@Till: Well it is fine, but a FQDN ends with a dot. In bind config you have 2 possibilties, to attach the zone (with the trailing .) to each record, or the shortened syntax, where bind does this automatically.