wal-land.cn. 30 IN SOA . hostmaster.nameserver. ( 29 ; serial 28800 ; refresh (8 hours) 7200 ; retry (2 hours) 604800 ; expire (1 week) 5 ; minimum (5 seconds) ) Mail exchangers: wal-land.cn. 30 IN MX 10 mail.wal-land.cn.