[ApiController]
[Route("[controller]")]
public class ScenarioOneController : ControllerBase
    [HttpGet()]
    public async Task<ActionResult> Get()
        var client = new HttpClient
            BaseAddress = new Uri("https://jsonplaceholder.typicode.com/"),
            DefaultRequestHeaders = { { "accept", "application/json" } },
            Timeout = TimeSpan.FromSeconds(15)
        var response = await client.GetAsync(
            "posts/1/comments");
        if (response.IsSuccessStatusCode) 
            return Ok(await response.Content.ReadAsStringAsync());
        return StatusCode(500);

[ApiController]
[Route("[controller]")]
public class ScenarioTwoController : ControllerBase
    [HttpGet()]
    public async Task<ActionResult> Get()
        using var client = new HttpClient
            BaseAddress = new Uri("https://jsonplaceholder.typicode.com/"),
            DefaultRequestHeaders = { { "accept", "application/json" } },
            Timeout = TimeSpan.FromSeconds(15)
        var response = await client.GetAsync(
            "posts/1/comments");
        if (response.IsSuccessStatusCode)
            return Ok(await response.Content.ReadAsStringAsync());
        return StatusCode(500);

[ApiController]
[Route("[controller]")]
public class ScenarioThreeController : ControllerBase
    private static readonly HttpClient Client = new()
        BaseAddress = new Uri("https://jsonplaceholder.typicode.com/"),
        DefaultRequestHeaders = { { "accept", "application/json" } },
        Timeout = TimeSpan.FromSeconds(15),
    [HttpGet()]
    public async Task<ActionResult> Get()
        var response = await Client.GetAsync(
            "posts/1/comments");
        if (response.IsSuccessStatusCode)
            return Ok(await response.Content.ReadAsStringAsync());
        return StatusCode(500);

[ApiController]
[Route("[controller]")]
public class ScenarioFourController : ControllerBase
    private static readonly HttpClient Client = new(new SocketsHttpHandler
        PooledConnectionLifetime = TimeSpan.FromSeconds(10)
        BaseAddress = new Uri("https://jsonplaceholder.typicode.com/"),
        DefaultRequestHeaders = { { "accept", "application/json" } },
        Timeout = TimeSpan.FromSeconds(15),
    [HttpGet()]
    public async Task<ActionResult> Get()
        var response = await Client.GetAsync(
            "posts/1/comments");
        if (response.IsSuccessStatusCode)
            return Ok(await response.Content.ReadAsStringAsync());
        return StatusCode(500);

[ApiController]
[Route("[controller]")]
public class ScenarioFourController : ControllerBase
    private static readonly HttpClient Client = new(new SocketsHttpHandler
        PooledConnectionLifetime = TimeSpan.FromMinutes(30),
        PooledConnectionIdleTimeout = TimeSpan.FromSeconds(10)
        BaseAddress = new Uri("https://jsonplaceholder.typicode.com/"),
        DefaultRequestHeaders = { { "accept", "application/json" } },
        Timeout = TimeSpan.FromSeconds(15),
    [HttpGet()]
    public async Task<ActionResult> Get()
        var response = await Client.GetAsync(
            "posts/1/comments");
        if (response.IsSuccessStatusCode)
            return Ok(await response.Content.ReadAsStringAsync());
        return StatusCode(500);

builder.Services.AddHttpClient("typicode", c =>
    c.BaseAddress = new Uri("https://jsonplaceholder.typicode.com/");
    c.Timeout = TimeSpan.FromSeconds(15);
    c.DefaultRequestHeaders.Add(
        "accept", "application/json");
.SetHandlerLifetime(TimeSpan.FromSeconds(15));

[ApiController]
[Route("[controller]")]
public class ScenarioFiveController : ControllerBase
    private readonly IHttpClientFactory _factory;
    public ScenarioFiveController(IHttpClientFactory factory)
        _factory = factory;
    [HttpGet()]
    public async Task<ActionResult> Get()
        var client = _factory.CreateClient("typicode");
        var response = await client.GetAsync(
            "posts/1/comments");
        if (response.IsSuccessStatusCode)
            return Ok(await response.Content.ReadAsStringAsync());
        return StatusCode(500);

builder.Services.AddHttpClient("typicode", c =>
        c.BaseAddress = new Uri("https://jsonplaceholder.typicode.com/");
        c.Timeout = TimeSpan.FromSeconds(15);
        c.DefaultRequestHeaders.Add(
            "accept", "application/json");
    .ConfigurePrimaryHttpMessageHandler(() => new SocketsHttpHandler()
        PooledConnectionIdleTimeout = TimeSpan.FromMinutes(5)
    .SetHandlerLifetime(TimeSpan.FromMinutes(20));
Up to this point, we have only explored scenarios that affected .NET 5/6/7, but what if we want to use an HttpClient in an application built with .NET Framework 4.8?
The recommended way to use HttpClient in .NET Framework 4.8 is using IHttpClientFactory.**
**You can use a static or singleton HttpClient, if you are certain that you will not encounter DNS changes in the service you are calling.
Can we use a static or singleton HttpClient with the PooledConnectionLifetime attribute (like Scenario 4)?
No, we cannot. it doesn’t work with .NET Framework, the SocketsHttpHandler doesn’t exist in .NET Framework.

HttpClient is built on top of the pre-existing HttpWebRequest implementation, you could use the ServicePoint API to control and manage HTTP connections, including setting a connection lifetime by configuring the ConnectionLeaseTimeout for an endpoint.
Scenario 6: Using IHttpClientFactory with .NET Framework and Autofac
Source code
This scenario uses Autofac as IoC container.
An IHttpClientFactory named client is setup in the AutofacWebapiConfig.cs class.
A few additional steps are required to make IHttpClientFactory work with Autofac:
Add required packages:
Microsoft.Extensions.Http
IHttpClientFactory must be registered properly in Autofac IoC container. To do that, we must follow the next steps:
Create a new ServiceCollection instance.
Add the IHttpClientFactory named client.
Build the ServiceProvider and resolve IHttpClientFactory.
The IHttpClientFactory must be registered as a Singleton on Autofac, or it won’t work properly.
    AreaRegistration.RegisterAllAreas();
    AutofacWebapiConfig.Initialize(GlobalConfiguration.Configuration);
    GlobalConfiguration.Configure(WebApiConfig.Register);
    FilterConfig.RegisterGlobalFilters(GlobalFilters.Filters);
    RouteConfig.RegisterRoutes(RouteTable.Routes);
    BundleConfig.RegisterBundles(BundleTable.Bundles);

public class AutofacWebapiConfig
    public static IContainer Container;
    public static void Initialize(HttpConfiguration config)
        Initialize(config, RegisterServices(new ContainerBuilder()));
    public static void Initialize(HttpConfiguration config, IContainer container)
        config.DependencyResolver = new AutofacWebApiDependencyResolver(container);
    private static IContainer RegisterServices(ContainerBuilder builder)
        builder.RegisterApiControllers(Assembly.GetExecutingAssembly());
        builder.Register(ctx =>
            var services = new ServiceCollection();
            services.AddHttpClient("typicode", c =>
                c.BaseAddress = new Uri("https://jsonplaceholder.typicode.com/");
                c.Timeout = TimeSpan.FromSeconds(15);
                c.DefaultRequestHeaders.Add(
                    "accept", "application/json");
            .SetHandlerLifetime(TimeSpan.FromSeconds(15));
            var provider = services.BuildServiceProvider();
            return provider.GetRequiredService<IHttpClientFactory>();
        }).SingleInstance();
        Container = builder.Build();
        return Container;

 public class ScenarioSixController : ApiController
    private readonly IHttpClientFactory _factory;
    public ScenarioSixController(IHttpClientFactory factory)
        _factory = factory;
    public async Task<IHttpActionResult> Get()
        var client = _factory.CreateClient("typicode");
        var response = await client.GetAsync(
            "posts/1/comments");
        if (response.IsSuccessStatusCode)
            return Ok(await response.Content.ReadAsStringAsync());
        return InternalServerError();