diff --git a/dhclient-script b/dhclient-script
index fbc734a..f562378 100755
--- a/dhclient-script
+++ b/dhclient-script
@@ -89,6 +89,9 @@ make_resolv_conf() {
             if [ -n "${new_domain_search}" ]; then
                 echo "search ${new_domain_search//\\032/ }" >> ${rscf}
             elif [ -n "${new_domain_name}" ]; then
+                # Note that the DHCP 'Domain Name Option' is really just a domain
+                # name, and that this practice of using the domain name option as
+                # a search path is both nonstandard and deprecated.
                 echo "search ${new_domain_name//\\032/ }" >> ${rscf}
             fi
         fi
@@ -407,14 +410,11 @@ dhconfig() {
     fi
 }
 
-dh6config() {
-    case "${reason}" in
-        BOUND6)
-            if [ -z "${new_ip6_address}" ] &&
-               [ -z "${new_ip6_prefixlen}" ]; then
-                exit_with_hooks 2
-            fi
-
+# Section 18.1.8. (Receipt of Reply Messages) of RFC 3315 says:
+# The client SHOULD perform duplicate address detection on each of
+# the addresses in any IAs it receives in the Reply message before
+# using that address for traffic.
+add_ipv6_addr_with_DAD() {
             ip -6 addr add ${new_ip6_address}/${new_ip6_prefixlen} \
                 dev ${interface} scope global
 
@@ -439,11 +439,28 @@ dh6config() {
                 ip -6 addr del ${new_ip6_address}/${new_ip6_prefixlen} dev ${interface}
                 exit_with_hooks 3
             fi
+}
+
+dh6config() {
+    case "${reason}" in
+        BOUND6)
+            if [ -z "${new_ip6_address}" ] &&
+               [ -z "${new_ip6_prefixlen}" ]; then
+                exit_with_hooks 2
+            fi
+
+            add_ipv6_addr_with_DAD
 
             make_resolv_conf
             ;;
 
         RENEW6|REBIND6)
+            if [ -n "${new_ip6_prefixlen}" ] &&
+               [ -n "${new_ip6_address}" ] &&
+               [  ! "${new_ip6_address}" = "${old_ip6_address}" ]; then
+                add_ipv6_addr_with_DAD
+            fi
+
             if [ ! "${new_dhcp6_name_servers}" = "${old_dhcp6_name_servers}" ] ||
                [ ! "${new_dhcp6_domain_search}" = "${old_dhcp6_domain_search}" ]; then
                 make_resolv_conf
diff --git a/dhcp.spec b/dhcp.spec
index 5f76acc..7161db6 100644
--- a/dhcp.spec
+++ b/dhcp.spec
@@ -13,7 +13,7 @@
 Summary:  Dynamic host configuration protocol software
 Name:     dhcp
 Version:  %{basever}
-Release:  17%{?dist}
+Release:  18%{?dist}
 # NEVER CHANGE THE EPOCH on this package.  The previous maintainer (prior to
 # dcantrell maintaining the package) made incorrect use of the epoch and
 # that's why it is at 12 now.  It should have never been used, but it was.
@@ -226,6 +226,7 @@ libdhcpctl and libomapi static libraries are also included in this package.
 %patch24 -p1 -b .retransmission
 
 # Fill in Elapsed Time Option in Release message (#582939)
+# (Submitted to dhcp-bugs@isc.org - [ISC-Bugs #21171])
 %patch25 -p1 -b .release6-elapsed
 
 # Copy in documentation and example scripts for LDAP patch to dhcpd
@@ -510,6 +511,10 @@ fi
 %attr(0644,root,root) %{_mandir}/man3/omapi.3.gz
 
 %changelog
+* Wed Apr 21 2010 Jiri Popelka <jpopelka@redhat.com> - 12:4.1.1-18
+- If the Reply was received in response to Renew or Rebind message,
+  client adds any new addresses in the IA option to the IA (#578097)
+
 * Mon Apr 19 2010 Jiri Popelka <jpopelka@redhat.com> - 12:4.1.1-17
 - Fill in Elapsed Time Option in Release/Decline messages (#582939)