diff --git a/ChangeLog b/ChangeLog
index d8cd7ecc8d..1dbc914e04 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+Fri Oct  9 21:14:40 2009  Tanaka Akira  <akr@fsij.org>
+
+	* lib/resolv.rb (Resolv::DNS::Requester::ConnectedUDP): disable
+	  reverse lookup.
+	  (Resolv::DNS::Requester::UnconnectedUDP): ditto.
+
 Fri Oct  9 10:12:13 2009  NARUSE, Yui  <naruse@ruby-lang.org>
 
 	* lib/irb/context.rb (IRB::Context#initialize):
diff --git a/lib/resolv.rb b/lib/resolv.rb
index 265a4b7f0c..9a65746959 100644
--- a/lib/resolv.rb
+++ b/lib/resolv.rb
@@ -655,6 +655,7 @@ class Resolv
         def initialize
           super()
           @sock = UDPSocket.new
+          @sock.do_not_reverse_lookup = true
           @sock.fcntl(Fcntl::F_SETFD, Fcntl::FD_CLOEXEC) if defined? Fcntl::F_SETFD
           DNS.bind_random_port(@sock)
         end
@@ -701,9 +702,10 @@ class Resolv
           @port = port
           is_ipv6 = host.index(':')
           @sock = UDPSocket.new(is_ipv6 ? Socket::AF_INET6 : Socket::AF_INET)
+          @sock.do_not_reverse_lookup = true
+          @sock.fcntl(Fcntl::F_SETFD, Fcntl::FD_CLOEXEC) if defined? Fcntl::F_SETFD
           DNS.bind_random_port(@sock, is_ipv6)
           @sock.connect(host, port)
-          @sock.fcntl(Fcntl::F_SETFD, Fcntl::FD_CLOEXEC) if defined? Fcntl::F_SETFD
         end
 
         def recv_reply