How to check to make sure a URL is valid

If you have users enter URLs and you would like to check them to make sure they exist before you save them to the database, here is the code:

public static bool UrlIsValid(string smtpHost)
    bool br = false;
    try {
        IPHostEntry ipHost = Dns.Resolve(smtpHost);
        br = true;
    catch (SocketException se) {
        br = false;
    return br;

To use, simply call UrlIsValid with the host name, for example:

string url = "";
if(UrlIsValid(url)) {
    Response.Write("The URL '" + url + "' is valid.");
} else {
    Response.Write("The URL '" + url + "' is NOT valid.");

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