diff --git a/Doc/library/http.server.rst b/Doc/library/http.server.rst
--- a/Doc/library/http.server.rst
+++ b/Doc/library/http.server.rst
@@ -269,8 +269,11 @@
 
    .. method:: address_string()
 
-      Returns the client address, formatted for logging. A name lookup is
-      performed on the client's IP address.
+      Returns the client address.
+
+      .. versionchanged:: 3.3
+         Previously, a name lookup was performed. To avoid name resolution
+         delays, it now always returns the IP address.
 
 
 .. class:: SimpleHTTPRequestHandler(request, client_address, server)
diff --git a/Lib/http/server.py b/Lib/http/server.py
--- a/Lib/http/server.py
+++ b/Lib/http/server.py
@@ -558,15 +558,9 @@
                  'Jul', 'Aug', 'Sep', 'Oct', 'Nov', 'Dec']
 
     def address_string(self):
-        """Return the client address formatted for logging.
+        """Return the client address."""
 
-        This version looks up the full hostname using gethostbyaddr(),
-        and tries to find a name that contains at least one dot.
-
-        """
-
-        host, port = self.client_address[:2]
-        return socket.getfqdn(host)
+        return self.client_address[0]
 
     # Essentially static class variables
 
@@ -1035,9 +1029,6 @@
         env['SCRIPT_NAME'] = scriptname
         if query:
             env['QUERY_STRING'] = query
-        host = self.address_string()
-        if host != self.client_address[0]:
-            env['REMOTE_HOST'] = host
         env['REMOTE_ADDR'] = self.client_address[0]
         authorization = self.headers.get("authorization")
         if authorization: