diff --git a/samba/templates/domain.conf-bdc.erb b/samba/templates/domain.conf-bdc.erb
index eee4969..bb2c0cd 100644
--- a/samba/templates/domain.conf-bdc.erb
+++ b/samba/templates/domain.conf-bdc.erb
@@ -2,6 +2,7 @@
 os level = 130
 
 max protocol = NT1
+server signing = mandatory
 
 domain master = no
 domain logons = yes
diff --git a/samba/templates/domain.conf-pdc.erb b/samba/templates/domain.conf-pdc.erb
index e5a054b..b2c189f 100644
--- a/samba/templates/domain.conf-pdc.erb
+++ b/samba/templates/domain.conf-pdc.erb
@@ -2,6 +2,7 @@
 os level = 140
 
 max protocol = NT1
+server signing = mandatory
 
 domain master = yes
 preferred master = yes