diff --git a/actionpack/CHANGELOG b/actionpack/CHANGELOG
index c77c4d3329..db3ad9662b 100644
--- a/actionpack/CHANGELOG
+++ b/actionpack/CHANGELOG
@@ -1,5 +1,7 @@
 *SVN*
 
+* AbstractRequest#domain returns nil when host is an ip address #2012 [kevin.clark@gmail.com]
+
 * ActionController documentation update #2051 [fbeausoleil@ftml.net]
 
 * Yield @content_for_ variables to templates #2058 [Sam Stephenson]
diff --git a/actionpack/lib/action_controller/request.rb b/actionpack/lib/action_controller/request.rb
index 3a29834b42..ca8dfff161 100755
--- a/actionpack/lib/action_controller/request.rb
+++ b/actionpack/lib/action_controller/request.rb
@@ -109,6 +109,8 @@ def remote_ip
     # Returns the domain part of a host, such as rubyonrails.org in "www.rubyonrails.org". You can specify
     # a different <tt>tld_length</tt>, such as 2 to catch rubyonrails.co.uk in "www.rubyonrails.co.uk".
     def domain(tld_length = 1)
+      return nil if !/\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}/.match(host).nil?
+        
       host.split('.').last(1 + tld_length).join('.')
     end
 
diff --git a/actionpack/test/controller/request_test.rb b/actionpack/test/controller/request_test.rb
index 8b079df5dd..5bb5bc3469 100644
--- a/actionpack/test/controller/request_test.rb
+++ b/actionpack/test/controller/request_test.rb
@@ -44,6 +44,9 @@ def test_domains
 
     @request.host = "www.rubyonrails.co.uk"
     assert_equal "rubyonrails.co.uk", @request.domain(2)
+    
+    @request.host = "192.168.1.200"
+    assert_nil @request.domain
   end
 
   def test_subdomains