前二節證實與說明，dot net core 在做相關的工作，會利用Singleton來保留相關的設定。而在整個Host要Build 起來的過程中，會有一定數量的 Singleton Service被註冊到IOC Container裡頭。
類似Singleton的Sevice整理如下供參考:

Microsoft.Extensions.Hosting.IHostingEnvironment
Microsoft.Extensions.Hosting.IHostEnvironment
Microsoft.Extensions.Hosting.HostBuilderContext
Microsoft.Extensions.Configuration.IConfiguration
Microsoft.Extensions.Hosting.IApplicationLifetime
Microsoft.Extensions.Hosting.IHostApplicationLifetime
Microsoft.Extensions.Hosting.IHostLifetime
Microsoft.Extensions.Hosting.IHost
Microsoft.Extensions.Logging.ILoggerFactory
Microsoft.Extensions.Logging.Configuration.ILoggerProviderConfigurationFactory
Microsoft.Extensions.Logging.Configuration.LoggingConfiguration
Microsoft.Extensions.Logging.ILoggerProvider
Microsoft.Extensions.Logging.EventSource.LoggingEventSource
Microsoft.AspNetCore.Hosting.IWebHostEnvironment
Microsoft.AspNetCore.Hosting.IHostingEnvironment
Microsoft.AspNetCore.Hosting.IApplicationLifetime
System.Diagnostics.DiagnosticListener
System.Diagnostics.DiagnosticSource
Microsoft.AspNetCore.Http.IHttpContextFactory
Microsoft.AspNetCore.Hosting.Builder.IApplicationBuilderFactory
Microsoft.AspNetCore.Connections.IConnectionListenerFactory
Microsoft.AspNetCore.Hosting.Server.IServer
Microsoft.AspNetCore.Routing.RoutingMarkerService
Microsoft.AspNetCore.Routing.EndpointDataSource
Microsoft.AspNetCore.Routing.ParameterPolicyFactory
Microsoft.AspNetCore.Routing.Matching.MatcherFactory
Microsoft.AspNetCore.Routing.Internal.DfaGraphWriter
Microsoft.AspNetCore.Routing.Matching.EndpointMetadataComparer
Microsoft.AspNetCore.Routing.LinkGenerator
Microsoft.AspNetCore.Routing.LinkParser
Microsoft.AspNetCore.Routing.Matching.EndpointSelector
Microsoft.AspNetCore.Routing.MatcherPolicy
Microsoft.AspNetCore.Routing.Template.TemplateBinderFactory
Microsoft.AspNetCore.Routing.Patterns.RoutePatternTransformer
Microsoft.AspNetCore.Server.IIS.Core.IISNativeApplication
Microsoft.AspNetCore.Hosting.IStartupFilter
Microsoft.AspNetCore.Authentication.IClaimsTransformation
Microsoft.AspNetCore.Authentication.IAuthenticationSchemeProvider
Microsoft.AspNetCore.Hosting.Server.IServerIntegratedAuth
Microsoft.AspNetCore.Mvc.ApplicationParts.ApplicationPartManager
Microsoft.AspNetCore.Mvc.ApplicationModels.ApplicationModelFactory
Microsoft.AspNetCore.Mvc.Infrastructure.IActionDescriptorCollectionProvider
Microsoft.AspNetCore.Mvc.Infrastructure.IActionSelector
Microsoft.AspNetCore.Mvc.ActionConstraints.ActionConstraintCache
Microsoft.AspNetCore.Mvc.Controllers.IControllerFactory
Microsoft.AspNetCore.Mvc.Controllers.IControllerFactoryProvider
Microsoft.AspNetCore.Mvc.Controllers.IControllerActivatorProvider
Microsoft.AspNetCore.Mvc.Infrastructure.IActionInvokerFactory
Microsoft.AspNetCore.Mvc.Infrastructure.ControllerActionInvokerCache
Microsoft.AspNetCore.Mvc.Filters.IFilterProvider
Microsoft.AspNetCore.Mvc.Infrastructure.IActionResultTypeMapper
Microsoft.AspNetCore.Mvc.ModelBinding.IModelMetadataProvider
Microsoft.AspNetCore.Mvc.ModelBinding.IModelBinderFactory
Microsoft.AspNetCore.Mvc.ModelBinding.Validation.IObjectModelValidator
Microsoft.AspNetCore.Mvc.ModelBinding.Validation.ClientValidatorCache
Microsoft.AspNetCore.Mvc.ModelBinding.ParameterBinder
Microsoft.Extensions.DependencyInjection.MvcMarkerService
Microsoft.AspNetCore.Mvc.Infrastructure.ITypeActivatorCache
Microsoft.AspNetCore.Mvc.Routing.IUrlHelperFactory
Microsoft.AspNetCore.Mvc.Infrastructure.IHttpRequestStreamReaderFactory
Microsoft.AspNetCore.Mvc.Infrastructure.IHttpResponseStreamWriterFactory
Microsoft.AspNetCore.Mvc.Infrastructure.OutputFormatterSelector
Microsoft.AspNetCore.Mvc.Infrastructure.IActionResultExecutor
Microsoft.AspNetCore.Mvc.Infrastructure.IClientErrorFactory
Microsoft.AspNetCore.Mvc.Infrastructure.ProblemDetailsFactory
Microsoft.AspNetCore.Mvc.Routing.ControllerActionEndpointDataSource
Microsoft.AspNetCore.Mvc.Routing.ActionEndpointFactory
Microsoft.AspNetCore.Mvc.Routing.DynamicControllerEndpointSelector
Microsoft.AspNetCore.Mvc.Filters.MiddlewareFilterConfigurationProvider
Microsoft.AspNetCore.Mvc.Filters.MiddlewareFilterBuilder
Microsoft.AspNetCore.Mvc.ApiExplorer.IApiDescriptionGroupCollectionProvider
Microsoft.AspNetCore.Authorization.Policy.AuthorizationPolicyMarkerService
Microsoft.AspNetCore.Mvc.DataAnnotations.IValidationAttributeAdapterProvider
Microsoft.AspNetCore.Mvc.Formatters.FormatFilter
Microsoft.AspNetCore.Hosting.GenericWebHostServiceOptions
Microsoft.Extensions.Hosting.IhostedService

以上做個紀錄供未來參考。