webmail redirection not working

[kini]

I'm sorry for this post but.. I also have this problem.. When i try to open mail.domain.com is opening sentora's login page..

mail.domain.com is supposed to show panel login. it is your mail server domain.
webmail.domain.com is what should point to roundcube.

That's good! But what kind of dns record i need to add for make webmail. for roundcube ?

EDIT:

and always dns manager have this error:

DNS Status for domain: domain.com


Errors detected have prevented your DNS zone from being loaded. Please correct the error(s) listed below. Until these errors are fixed, your DNS will not work.

Please note that changes to your zone records can take up to 24 hours before they become 'live'.

Output of DNS zone checker:


Warning log show this:

20-Mar-2015 21:43:08.975 general: warning: managed-keys-zone: Unable to fetch DNSKEY set 'dlv.isc.org': timed out
20-Mar-2015 22:43:18.975 general: warning: managed-keys-zone: Unable to fetch DNSKEY set 'dlv.isc.org': timed out
20-Mar-2015 23:43:28.976 general: warning: managed-keys-zone: Unable to fetch DNSKEY set 'dlv.isc.org': timed out
21-Mar-2015 00:43:38.977 general: warning: managed-keys-zone: Unable to fetch DNSKEY set 'dlv.isc.org': timed out
21-Mar-2015 01:43:48.977 general: warning: managed-keys-zone: Unable to fetch DNSKEY set 'dlv.isc.org': timed out
21-Mar-2015 02:43:58.978 general: warning: managed-keys-zone: Unable to fetch DNSKEY set 'dlv.isc.org': timed out
21-Mar-2015 03:44:08.979 general: warning: managed-keys-zone: Unable to fetch DNSKEY set 'dlv.isc.org': timed out
21-Mar-2015 04:44:18.980 general: warning: managed-keys-zone: Unable to fetch DNSKEY set 'dlv.isc.org': timed out