One can use below mentioned asp.net code to change absolute path into relative path:

Dim Domname,link,str,temp as string

Domname = "http://Domain.com"
ObjDoc = Server.CreateObject ("MSXML2.DOMDocument.4.0")
objDoc.Async = False
ObjHTTP = Server.CreateObject ("XStandard.HTTP")
objHTTP.AddRequestHeader ("User-Agent", "Mozilla/4.0 (compatible; MyApp 1.0; Windows NT 5.1)")
objHTTP.Get ("http://Domain.com")
str = ""

If objDoc.LoadXML (objHTTP.ResponseAsXML) Then
For Each objNode In objDoc.SelectNodes ("//a[string (@src)!= ]")
link = objNode.Attributes.GetNamedItem ("href").Text
temp = link

If InStr (link, "..") > 0 Then
link = Mid (link, InStr(img, "/") + 1)
End If
Path = domname & "/"
Path += link
objHTTP.Get (Path
Next
End if

This code will change all the absolute path of a tag into the relative path of the site Domain.Com.