Best practices for multi language site across different sub domains

Question

I am looking to build a site in ASP.NET. I need it to be in french and english with the domains setup like so:

en.mysite.com fr.mysite.com

I do not want to

Answer 1

My solution was setting the lang in the BeginRequest in global.asax

Sub Application_BeginRequest(ByVal sender As Object, ByVal e As EventArgs)
    Dim lang As String = "es" ''//default
    If Request.Url.ToString.ToLower.StartsWith("http://es.") 
        lang = "es"
    ElseIf Request.Url.ToString.ToLower.StartsWith("http://en.") Then
        lang = "en"
    End If
    Thread.CurrentThread.CurrentUICulture = CultureInfo.GetCultureInfo(lang)
    Thread.CurrentThread.CurrentCulture = CultureInfo.CreateSpecificCulture(lang)

    Site.Idioma = lang ''//static variable that I use in other parts of the site
End Sub

Do not forget to set a redirect when the user hits www.mysite.com, using the user's browser language preference

Imports System.Globalization
Partial Class redirect_Default
    Inherits System.Web.UI.Page

    Protected Sub Page_Load(ByVal s As Object, ByVal e As System.EventArgs) _
                                                                 Handles Me.Load

        Select Case Mid(Request.UserLanguages(0).ToString(), 1, 2).ToLower
            Case "en"
                Response.Redirect("http://en.mysite.com")
            Case Else
                Response.Redirect("http://es.mysite.com")
        End Select

    End Sub
End Class

As a side point, I recommend you to use http://www.mysite.com/en because it is better from the SEO perspective (If it is important to your site)