就是一个判断本机与某个IP地址、某个电脑是否连通，从而可以判断本机是否在某个网段上，也可以通过ping外网的地址来判断本机是否连网，也可以用来检测某个网站是否还存在可以访问。
资源文件列表
WindowsFormsApplication2.v11.suo , 11776
WindowsFormsApplication2/App.config , 189
WindowsFormsApplication2/bin/Debug/WindowsFormsApplication2.exe , 9728
WindowsFormsApplication2/bin/Debug/WindowsFormsApplication2.exe.config , 189
WindowsFormsApplication2/bin/Debug/WindowsFormsApplication2.pdb , 26112
WindowsFormsApplication2/bin/Debug/WindowsFormsApplication2.vshost.exe , 22984
WindowsFormsApplication2/bin/Debug/WindowsFormsApplication2.vshost.exe.config , 189
WindowsFormsApplication2/bin/Debug/WindowsFormsApplication2.vshost.exe.manifest , 490
WindowsFormsApplication2/Form1.cs , 1218
WindowsFormsApplication2/Form1.Designer.cs , 4002
WindowsFormsApplication2/Form1.resx , 5817
WindowsFormsApplication2/obj/Debug/DesignTimeResolveAssemblyReferences.cache , 867
WindowsFormsApplication2/obj/Debug/DesignTimeResolveAssemblyReferencesInput.cache , 7214
WindowsFormsApplication2/obj/Debug/TemporaryGeneratedFile_036C0B5B-1481-4323-8D20-8F5ADCB23D92.cs , 0
WindowsFormsApplication2/obj/Debug/TemporaryGeneratedFile_5937a670-0e60-4077-877b-f7221da3dda1.cs , 0
WindowsFormsApplication2/obj/Debug/TemporaryGeneratedFile_E7A71F73-0F8D-4B9B-B56E-8E70B10BC5D3.cs , 0
WindowsFormsApplication2/obj/Debug/WindowsFormsApplication2.csproj.FileListAbsolute.txt , 1302
WindowsFormsApplication2/obj/Debug/WindowsFormsApplication2.csproj.GenerateResource.Cache , 975
WindowsFormsApplication2/obj/Debug/WindowsFormsApplication2.csprojResolveAssemblyReference.cache , 2231
WindowsFormsApplication2/obj/Debug/WindowsFormsApplication2.exe , 9728
WindowsFormsApplication2/obj/Debug/WindowsFormsApplication2.Form1.resources , 180
WindowsFormsApplication2/obj/Debug/WindowsFormsApplication2.pdb , 26112
WindowsFormsApplication2/obj/Debug/WindowsFormsApplication2.Properties.Resources.resources , 180
WindowsFormsApplication2/Program.cs , 536
WindowsFormsApplication2/Properties/AssemblyInfo.cs , 1368
WindowsFormsApplication2/Properties/Resources.Designer.cs , 2900
WindowsFormsApplication2/Properties/Resources.resx , 5612
WindowsFormsApplication2/Properties/Settings.Designer.cs , 1111
WindowsFormsApplication2/Properties/Settings.settings , 249
WindowsFormsApplication2/WindowsFormsApplication2.csproj , 3829
WindowsFormsApplication2.sln , 962