Validate User Name and Password with Active Directory

public bool ValidateCredentials(string username, string password)

{

string adServer= "AD Server Name";

StringBuilder sb = new StringBuilder();

DirectoryEntry entry = new DirectoryEntry(adServer);//connect to server

DirectorySearcher search = new DirectorySearcher(entry);

string domain = System.Configuration.ConfigurationSettings.AppSettings["Domain"];

using (PrincipalContext pc = new PrincipalContext(ContextType.Domain, domain))

{

return pc.ValidateCredentials(username, password);

}

}