作为测试，我设置了网络以模拟"Internet"通过将单个服务器连接到外部接口来模拟局域网和局域网（模拟ISP DHCP& DNS server, and default gateway) and a few computers connected to the inside interfaces (simulating the local LAN). I was surprised when I noticed that when I pinged the external IP address from the outside server that I received a response. Though this isn't a huge deal, in a production environment it would reveal your availability on 互联网. I was able to easily block ICMP packets on the outside interface but that got me wondering if other non-critical, but noteworthy features on the firewall need to be adjusted as well. I do plan on eventually getting a book on the ASA but for now I have to learn by trail and error and reading information here and there.