Sub HighlightInvalidLinks()
  Dim objLink As Hyperlink
  Dim strLinkAddress As String
  Dim strResult As String
  Dim objDoc As Document
 
  Set objDoc = ActiveDocument
 
  With objDoc
    For Each objLink In .Hyperlinks
      strLinkAddress = objLink.Address
 
      If Not CheckURL(strLinkAddress) Then
        objLink.Range.HighlightColorIndex = wdYellow
      End If
    Next objLink
  End With
End Sub