A security analyst is reviewing the following vulnerability assessment report:
192.168.1.5, Host = Server1, CVSS 7.5, Web Server, Remotely Executable = Yes, Exploit = Yes
205.1.3.5, Host = Server2, CVSS 6.5, Bind Server, Remotely Executable = Yes, Exploit = POC
207.1.5.7, Host = Server3, CVSS 5.5, Email Server, Remotely Executable = Yes, Exploit = Yes
192.168.1.6, Host = Server4, CVSS 9.8, Domain Controller, Remotely Executable = Yes, Exploit = Yes
Which of the following should be patched first to minimize attacks against internet-facing hosts?