问题：

[多选] You need to configure the DNS server to allow delivery of e-mail messages. Which four actions should you perform？（）

A . Create a host （A） resource record for EX1.fourthcoffee.com on the internal DNS Server
B . Create a host （A） resource record for EX1.fourthcoffee.com on the external DNS Server
C . Create a host （A） resource record for EX3.fourthcoffee.com on the internal DNS Server
D . Create a host （A） resource record for EX3.fourthcoffee.com on the external DNS Server
E . Create a mail exchange （MX） resource record for EX1.fourthcoffee.com on the external DNS server. Set the preference to 10
F . Create a mail exchanger （MX） resource record for EX1.fourthcoffee.com on the internal DNS server. Set the preference to 10
G . Create a mail exchanger （MX） resource record for EX3.fourthcoffee.com on the external DNS server. Set the preference to 20
H . Create a mail exchanger （MX） resource record for EX3.fourthcoffee.com on the internal DNS server. Set the preference to 20