Code: @ IN SOA ns1.mirex.vn. quannv.vietinfotech.net. ( 2009051105 ; Serial 28800 ; Refresh 7200 ; Retry 604800 ; Expire 86400 ) ; Minimum mail 86400 IN CNAME ghs.google.com. mirex.vn. 86400 IN A 210.245.85.211 mirex.vn. 86400 IN MX 10 ASPMX.L.GOOGLE.COM. mirex.vn. 86400 IN NS ns1.mirex.vn. mirex.vn. 86400 IN NS ns2.mirex.vn. www 86400 IN A 210.245.85.211 But I can not ping mail.mirex.vn. I don't know why
Most likely the google server does not answer on pings. This does not mean that anything is wrong with mydns.
But what is your problem? Pinging a mailserver is not a test for a correct mailserver setup, so if ping does not work it does not mean that there is a problem at all.