diff --git a/server/InterfaceController.cpp b/server/InterfaceController.cpp
index b38c137..b7a4d0b 100644
--- a/server/InterfaceController.cpp
+++ b/server/InterfaceController.cpp
@@ -38,6 +38,9 @@
 	setAcceptRA("2");
 
 	setAcceptRARouteTable(-RouteController::ROUTE_TABLE_OFFSET_FROM_INDEX);
+
+	// Enable optimistic DAD for IPv6 addresses on all interfaces.
+	setIPv6OptimisticMode("1");
 }
 
 InterfaceController::~InterfaceController() {
@@ -147,3 +150,8 @@
 	free(path);
 	return success;
 }
+
+void InterfaceController::setIPv6OptimisticMode(const char *value) {
+	setOnAllInterfaces("optimistic_dad", value);
+	setOnAllInterfaces("use_optimistic", value);
+}