Resolve HostName to IP

I have been through a lot of googling for this, I found a lot of examples none of which was working for me. This is a simple issue which I feel has a simple answer without defining new classes\modules etc...

My code is this :

Console.WriteLine ("Please enter an IP address or hostname");
string host = Console.ReadLine ();
***IP = resolved "host"*** 
Socket s = new Socket (AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.IP);    
s.Connect (IP, 80);
s.close();

How do I actually resolve the IP variable?

You can simply use the DNS class to do so:

IPHostEntry hostEntry;

hostEntry= Dns.GetHostEntry(host);

//you might get more than one ip for a hostname since 
//DNS supports more than one record

if (hostEntry.AddressList.Length > 0)
{
      var ip = hostEntry.AddressList[0];
      Socket s = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.IP);
      s.Connect(ip, 80);
}

string howtogeek = "www.howtogeek.com";
IPAddress[] addresslist = Dns.GetHostAddresses(howtogeek);

foreach (IPAddress theaddress in addresslist)
{
   Console.WriteLine(theaddress.ToString());
 }

from howtogeek

Please take the note that accepted answer can resolve to IPv6. I attempted to connect to service that does not accept IPv6 as input string.

Therefore try this snippet if you care to get IPv4:

using System.Linq;

string host = "google.com";

Dns.GetHostEntry(host).AddressList.First(addr => addr.AddressFamily == System.Net.Sockets.AddressFamily.InterNetwork)

This is the method I use to resolve a hostname to IPv4 and / or IPv6.

    using System.Net:

    // A host can have multiple IP addresses!
    public static IPAddress[] GetIPsByName(string hostName, bool ip4Wanted, bool ip6Wanted)
    {
        // Check if the hostname is already an IPAddress
        IPAddress outIpAddress;
        if (IPAddress.TryParse(hostName, out outIpAddress) == true)
            return new IPAddress[] { outIpAddress };
        //<----------

        IPAddress[] addresslist = Dns.GetHostAddresses(hostName);

        if (addresslist == null || addresslist.Length == 0)
            return new IPAddress[0];
        //<----------

        if (ip4Wanted && ip6Wanted)
            return addresslist;
        //<----------

        if (ip4Wanted)
            return addresslist.Where(o => o.AddressFamily == AddressFamily.InterNetwork).ToArray();
        //<----------

        if (ip6Wanted)
            return addresslist.Where(o => o.AddressFamily == AddressFamily.InterNetworkV6).ToArray();
        //<----------

        return new IPAddress[0];
    }