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Asked: 2026-06-11T07:42:41+00:00

I am trying to filter out invalid url from valid ones using .NET. I

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I am trying to filter out invalid url from valid ones using .NET.

I am using Uri.TryCreate() method for this.

It has the following syntax

public static bool TryCreate(Uri baseUri,string relativeUri,out Uri result)

Now I am doing this….

Uri uri = null;

var domainList = new List<string>();
domainList.Add("asas");
domainList.Add("www.stackoverflow.com");
domainList.Add("www.codera.org");
domainList.Add("www.joker.testtest");
domainList.Add("about.me");
domainList.Add("www.ma.tt");

var correctList = new List<string>();

foreach (var item in domainList)
{
    if(Uri.TryCreate(item, UriKind.RelativeOrAbsolute, out uri))
    {    
        correctList.Add(item);
    }
}

I am trying the above code I expect it to remove asas and www.joker.testtest from the list, but it doesnt.

Can some one help me out on this.

Update :
just tried out with Uri.IsWellFormedUriString this too did’nt help.

More Update

List of Valid uri

List of invalid uri

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1 Answer

  1. Editorial Team

    You seem to be confused about what exactly URL (or URI, the difference is not significant here) is. For example, http://stackoverflow.com is a valid absolute URL. On the other hand, stackoverflow.com is technically a valid relative URL, but it would refer to the file named stackoverflow.com in the current directory, not the website with that name. But stackoverflow.com is a registered domain name.

    If you want to check whether a domain name is valid, you need to define what exactly do you mean by “valid”:

    1. Is it a valid domain name? Check whether the string consists of parts separated by dots, each part can contain letters, numbers and a hyphen (-). For example, asas and this.not.valid are both valid domain names.
    2. Could it be an Internet domain name? Domain names on the Internet (as opposed to intranet) are specific in that they always have a TLD (top-level domain). So, asas certainly isn’t an Internet domain name, but this.not.valid could be.
    3. Is it a domain name under existing TLD? You can download the list of all TLDs and check against that. For example, this.not.valid wouldn’t be considered valid under this rule, but thisisnotvalid.com would.
    4. Is it a registered domain name?
    5. Does the domain name resolve to an IP address? A domain name could be registered, but it still may not have an IP address in its DNS record.
    6. Does the computer the domain name points to respond to requests? The requests that make the most sense are a simple HTTP request (e.g. trying to access http://domaininquestion/) or ping.
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