A.基于IPsec的VPN B.基于PPTP的VPN C.基于L2TP的VPN D.基于SSH的VPN
A./etc/mail/local-hosts-names B./etc/mail/sendmail.cw C./etc/mail/aliases D./etc/mail/access
A./etc/named.conf B./etc/mail/sendmail.cf C./etc/mail/sendmail.cw D./etc/mail/sendmail.mc