Preface

How to know whether the external site is running ？

If you use a browser , Directly visit the corresponding site .

that , Use C# Programmatically , How to achieve it ？

GET request

First thought , Is the use of HttpClient Send to this site HTTP request , And check the return status ：

var httpClient = new HttpClient();  
var result = await httpClient.GetAsync("http://somesite.xxx");
Console.WriteLine(result.IsSuccessStatusCode);

however ,GET The request will return the response body , It will consume certain bandwidth resources .

HEAD request

Ways to improve , It's using HEAD request , It does not return the response body ：

var httpClient = new HttpClient();
var request = new HttpRequestMessage
{
    RequestUri = new Uri("http://somesite.xxx"),
    Method = HttpMethod.Head
};
var result = await httpClient.SendAsync(request);
Console.WriteLine(result.IsSuccessStatusCode);

however , There will also be some problems , For example, the site needs authentication , The above code will return false, Even if the site is running .

Ping

When using the command line , Can run ping Command and view the results :

C# You can also use Ping：

Ping ping = new Ping();
var hostName = new Uri("http://somesite.xxx").Host;

var result = await ping.SendPingAsync(hostName);
Console.WriteLine(result.Status == IPStatus.Success);

It should be noted that , If the site turns on the firewall , It's forbidden ping Ordered ICMP Echo message , The above code will return false.

Conclusion

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