Present the rules for the external and internal firewall in a table format
a) Email may be sent using SMTP in both directions through the firewall, but it must be relayed via the DMZ mail gateway. External email must be destined for the DMZ mail server.
b) Users inside may retrieve their e-mail from the DMZ mail gateway, using either POP3 or POP3S
c) Users outside my retrieve their email from the DMZ mail gateway, but only if they use the secure POP3 (POP3S) protocol.
d) Web requests are allowed from any internal user out through the firewall but must be relayed via the DMZ Web proxy, which provides content filtering.
e) Web requests are allowed from anywhere on the Internet to the DMZ Web server.
f) DNS lookup requests are allowed via the DMZ DNS server, which queries to the internet.
g) External DNS requests are provided by the DMZ DNS server