diff --git a/scripts/dns.sh b/scripts/dns.sh
index 8787dae8..0b5f0f15 100644
--- a/scripts/dns.sh
+++ b/scripts/dns.sh
@@ -11,30 +11,11 @@
 
 apt-get -qq -y install nsd3
 
-# Get configuraton information.
-
-if [ -z "$PUBLIC_HOSTNAME" ]; then
-	PUBLIC_HOSTNAME=example.org
-fi
-
-if [ -z "$PUBLIC_IP" ]; then
-	# works on EC2 only...
-	PUBLIC_IP=`wget -q -O- http://instance-data/latest/meta-data/public-ipv4`
-fi
-
 # Prepare nsd3's configuration.
 
 sudo mkdir -p /var/run/nsd3
 mkdir -p "$STORAGE_ROOT/dns";
 
-# Store our desired IP address (to put in the zone files) for later.
-# Also store our primary hostname, which we'll use for all DKIM signatures
-# in case the user is only delegating MX and we aren't setting DKIM on
-# the main DNS.
-
-echo $PUBLIC_IP > $STORAGE_ROOT/dns/our_ip
-echo $PUBLIC_HOSTNAME > $STORAGE_ROOT/dns/primary_hostname
-
 # Create the default zone if it doesn't exist.
 
 if [ ! -f "$STORAGE_ROOT/dns/$PUBLIC_HOSTNAME.txt" ]; then
diff --git a/scripts/dns_update.sh b/scripts/dns_update.sh
index 3ff17399..8bc6f8e3 100755
--- a/scripts/dns_update.sh
+++ b/scripts/dns_update.sh
@@ -8,10 +8,7 @@
 
 # This script is safe to run on its own.
 
-# Load $STORAGE_ROOT, $PUBLIC_IP, and $PRIMARY_HOSTNAME.
-source /etc/mailinabox.conf
-PUBLIC_IP=`cat $STORAGE_ROOT/dns/our_ip`
-PRIMARY_HOSTNAME=`cat $STORAGE_ROOT/dns/primary_hostname`
+source /etc/mailinabox.conf # load global vars
 
 # Ensure a zone file exists for every domain name in use by a mail user.
 for mail_user in `tools/mail.py user`; do
@@ -69,7 +66,7 @@ for fn in $STORAGE_ROOT/dns/*.txt; do
 \$ORIGIN $zone.    ; default zone domain
 \$TTL 86400           ; default time to live
 
-@ IN SOA ns1.$PRIMARY_HOSTNAME. hostmaster.$PRIMARY_HOSTNAME. (
+@ IN SOA ns1.$PUBLIC_HOSTNAME. hostmaster.$PUBLIC_HOSTNAME. (
            $serial     ; serial number
            28800       ; Refresh
            7200        ; Retry
@@ -77,18 +74,18 @@ for fn in $STORAGE_ROOT/dns/*.txt; do
            86400       ; Min TTL
            )
 
-           NS          ns1.$PRIMARY_HOSTNAME.
-           NS          ns2.$PRIMARY_HOSTNAME.
+           NS          ns1.$PUBLIC_HOSTNAME.
+           NS          ns2.$PUBLIC_HOSTNAME.
            IN     A    $PUBLIC_IP
-           MX     10   $PRIMARY_HOSTNAME.
+           MX     10   $PUBLIC_HOSTNAME.
 
            300    TXT  "v=spf1 mx -all"
 
 www        IN     A    $PUBLIC_IP
 EOF
 
-	# In PRIMARY_HOSTNAME, also define ns1 and ns2.
-	if [ "$zone" = $PRIMARY_HOSTNAME ]; then
+	# In PUBLIC_HOSTNAME, also define ns1 and ns2.
+	if [ "$zone" = $PUBLIC_HOSTNAME ]; then
 		cat >> /etc/nsd3/zones/$fn2 << EOF;
 ns1        IN     A    $PUBLIC_IP
 ns2        IN     A    $PUBLIC_IP
@@ -112,12 +109,12 @@ EOF
 	# the selector, and the path to the private key.
 	#
 	# Just in case we don't actually host the DNS for all domains of our mail users,
-	# we assume that DKIM is at least configured in the DNS of $PRIMARY_HOSTNAME and
+	# we assume that DKIM is at least configured in the DNS of $PUBLIC_HOSTNAME and
 	# we use that host for all DKIM signatures.
 	#
 	# In SigningTable, we map every email address to a key record called $zone.
 	# Then we specify for the key record named $zone its domain, selector, and key.
-	echo "$zone $PRIMARY_HOSTNAME:mail:$STORAGE_ROOT/mail/dkim/mail.private" >> /etc/opendkim/KeyTable
+	echo "$zone $PUBLIC_HOSTNAME:mail:$STORAGE_ROOT/mail/dkim/mail.private" >> /etc/opendkim/KeyTable
 	echo "*@$zone $zone" >> /etc/opendkim/SigningTable
 
 done
diff --git a/scripts/start.sh b/scripts/start.sh
index 873cc3a2..9b640c23 100755
--- a/scripts/start.sh
+++ b/scripts/start.sh
@@ -50,6 +50,7 @@ fi
 cat > /etc/mailinabox.conf << EOF;
 STORAGE_ROOT=$STORAGE_ROOT
 PUBLIC_HOSTNAME=$PUBLIC_HOSTNAME
+PUBLIC_IP=$PUBLIC_IP
 EOF
 
 # Start service configuration.