名称或服务未知 （api.sendgrid.com:443）

问：

我时不时地在生产服务器上遇到这个奇怪的异常，我不知道为什么它会不断发生。我尝试联系提供商，但没有运气和 SendGrid。

它是 .NET 7.0 上的一个 ASP.NET Core Web API 应用程序，在 Rocky Linux 8 上运行 Dockerized（4.18.0-477.15.1.el8_8.x86_64)

SendGrid .NET 包的版本为 9.28.1

以下是完整的堆栈跟踪：

System.Net.Http.HttpRequestException: Name or service not known (api.sendgrid.com:443)
 ---> System.Net.Sockets.SocketException (0xFFFDFFFF): Name or service not known
   at System.Net.Sockets.Socket.AwaitableSocketAsyncEventArgs.ThrowException(SocketError error, CancellationToken cancellationToken)
   at System.Net.Sockets.Socket.AwaitableSocketAsyncEventArgs.System.Threading.Tasks.Sources.IValueTaskSource.GetResult(Int16 token)
   at System.Net.Sockets.Socket.<ConnectAsync>g__WaitForConnectWithCancellation|281_0(AwaitableSocketAsyncEventArgs saea, ValueTask connectTask, CancellationToken cancellationToken)
   at System.Net.Http.HttpConnectionPool.ConnectToTcpHostAsync(String host, Int32 port, HttpRequestMessage initialRequest, Boolean async, CancellationToken cancellationToken)
   --- End of inner exception stack trace ---
   at System.Net.Http.HttpConnectionPool.ConnectToTcpHostAsync(String host, Int32 port, HttpRequestMessage initialRequest, Boolean async, CancellationToken cancellationToken)
   at System.Net.Http.HttpConnectionPool.ConnectAsync(HttpRequestMessage request, Boolean async, CancellationToken cancellationToken)
   at System.Net.Http.HttpConnectionPool.CreateHttp11ConnectionAsync(HttpRequestMessage request, Boolean async, CancellationToken cancellationToken)
   at System.Net.Http.HttpConnectionPool.AddHttp11ConnectionAsync(QueueItem queueItem)
   at System.Threading.Tasks.TaskCompletionSourceWithCancellation`1.WaitWithCancellationAsync(CancellationToken cancellationToken)
   at System.Net.Http.HttpConnectionPool.HttpConnectionWaiter`1.WaitForConnectionAsync(Boolean async, CancellationToken requestCancellationToken)
   at System.Net.Http.HttpConnectionPool.SendWithVersionDetectionAndRetryAsync(HttpRequestMessage request, Boolean async, Boolean doRequestAuth, CancellationToken cancellationToken)
   at System.Net.Http.DiagnosticsHandler.SendAsyncCore(HttpRequestMessage request, Boolean async, CancellationToken cancellationToken)
   at System.Net.Http.RedirectHandler.SendAsync(HttpRequestMessage request, Boolean async, CancellationToken cancellationToken)
   at Microsoft.Extensions.Http.Logging.LoggingHttpMessageHandler.<SendAsync>g__Core|5_0(HttpRequestMessage request, CancellationToken cancellationToken)
   at Sentry.SentryMessageHandler.SendAsync(HttpRequestMessage request, CancellationToken cancellationToken)
   at Microsoft.Extensions.Http.Logging.LoggingScopeHttpMessageHandler.<SendAsync>g__Core|5_0(HttpRequestMessage request, CancellationToken cancellationToken)
   at System.Net.Http.HttpClient.<SendAsync>g__Core|83_0(HttpRequestMessage request, HttpCompletionOption completionOption, CancellationTokenSource cts, Boolean disposeCts, CancellationTokenSource pendingRequestsCts, CancellationToken originalCancellationToken)
   at SendGrid.BaseClient.MakeRequest(HttpRequestMessage request, CancellationToken cancellationToken)
   at SendGrid.BaseClient.RequestAsync(Method method, String requestBody, String queryParams, String urlPath, CancellationToken cancellationToken)
   at SendGrid.BaseClient.SendEmailAsync(SendGridMessage msg, CancellationToken cancellationToken)
   at Notifications.Utils.Mailer.SendMailAsync(SendGridMessage msg) in /src/Notifications/Utils/Mailer.cs:line 17
   at Notifications.MailNotificationService.SendLoginVerificationAsync(User user, String ipAddress, String token) in /src/Notifications/MailNotificationService.cs:line 322
   at Authentication.Services.AuthenticationService.LoginAsync(String email, String password, String ipAddress, String code) in /src/Authentication/Services/AuthenticationService.cs:line 144
   at Api.Controllers.AuthController.AuthenticateUserAsync(LoginUserForm userForm, CancellationToken token) in /src/Api/Controllers/AuthController.cs:line 140
   at Microsoft.AspNetCore.Mvc.Infrastructure.ActionMethodExecutor.TaskOfIActionResultExecutor.Execute(ActionContext actionContext, IActionResultTypeMapper mapper, ObjectMethodExecutor executor, Object controller, Object[] arguments)
   at Microsoft.AspNetCore.Mvc.Infrastructure.ControllerActionInvoker.<InvokeActionMethodAsync>g__Awaited|12_0(ControllerActionInvoker invoker, ValueTask`1 actionResultValueTask)
   at Microsoft.AspNetCore.Mvc.Infrastructure.ControllerActionInvoker.<InvokeNextActionFilterAsync>g__Awaited|10_0(ControllerActionInvoker invoker, Task lastTask, State next, Scope scope, Object state, Boolean isCompleted)
   at Microsoft.AspNetCore.Mvc.Infrastructure.ControllerActionInvoker.Rethrow(ActionExecutedContextSealed context)
   at Microsoft.AspNetCore.Mvc.Infrastructure.ControllerActionInvoker.Next(State& next, Scope& scope, Object& state, Boolean& isCompleted)
   at Microsoft.AspNetCore.Mvc.Infrastructure.ControllerActionInvoker.<InvokeInnerFilterAsync>g__Awaited|13_0(ControllerActionInvoker invoker, Task lastTask, State next, Scope scope, Object state, Boolean isCompleted)
   at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.<InvokeFilterPipelineAsync>g__Awaited|20_0(ResourceInvoker invoker, Task lastTask, State next, Scope scope, Object state, Boolean isCompleted)
   at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.<InvokeAsync>g__Awaited|17_0(ResourceInvoker invoker, Task task, IDisposable scope)
   at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.<InvokeAsync>g__Awaited|17_0(ResourceInvoker invoker, Task task, IDisposable scope)
   at Microsoft.AspNetCore.Routing.EndpointMiddleware.<Invoke>g__AwaitRequestTask|6_0(Endpoint endpoint, Task requestTask, ILogger logger)
   at Sentry.AspNetCore.SentryTracingMiddleware.InvokeAsync(HttpContext context)
   at Sentry.AspNetCore.SentryTracingMiddleware.InvokeAsync(HttpContext context)
   at Authentication.Middleware.ApiKeyVerificationMiddleware.InvokeAsync(HttpContext context, RequestDelegate next) in /src/Authentication/Middleware/ApiKeyVerification.cs:line 58
   at Microsoft.AspNetCore.Builder.UseMiddlewareExtensions.<>c__DisplayClass6_1.<<UseMiddlewareInterface>b__1>d.MoveNext()
--- End of stack trace from previous location ---
   at Microsoft.AspNetCore.Authorization.AuthorizationMiddleware.Invoke(HttpContext context)
   at Microsoft.AspNetCore.Authentication.AuthenticationMiddleware.Invoke(HttpContext context)
   at AspNetCoreRateLimit.RateLimitMiddleware`1.Invoke(HttpContext context) in C:\Users\User\Documents\Github\AspNetCoreRateLimit\src\AspNetCoreRateLimit\Middleware\RateLimitMiddleware.cs:line 125
   at Sentry.AspNetCore.SentryMiddleware.InvokeAsync(HttpContext context, RequestDelegate next)
   at Sentry.AspNetCore.SentryMiddleware.InvokeAsync(HttpContext context, RequestDelegate next)
   at Microsoft.AspNetCore.Builder.UseMiddlewareExtensions.<>c__DisplayClass6_1.<<UseMiddlewareInterface>b__1>d.MoveNext()
--- End of stack trace from previous location ---
   at Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http.HttpProtocol.ProcessRequests[TContext](IHttpApplication`1 application)

我最初认为主机上的DNS服务器是问题所在，它使用的是提供商的DNS服务器，所以我将它们切换到Cloudflares DNS服务器，但没有运气。

然后我尝试了谷歌的DNS服务器，但也没有帮助。最后，我安装了一个系统解析器（systemd-resolved），希望它能在某一时刻成功解决它，缓存结果，然后我们就会一帆风顺——这也无济于事。

在这一点上，我不知道该怎么做，我真的需要一些帮助来解决这个问题。