diff --git a/install.sh b/install.sh
index 67bcb2c..ec96035 100755
--- a/install.sh
+++ b/install.sh
@@ -13,6 +13,10 @@ openssl genrsa -out /etc/ssl/private/$APP.key 2048
 openssl req -new -key /etc/ssl/private/$APP.key -out /etc/ssl/certs/$APP.csr -config openssl.cnf
 openssl x509 -req -in /etc/ssl/certs/$APP.csr -CA /root/ca.crt -CAkey /root/ca.key -CAcreateserial -out /etc/ssl/certs/$APP.crt -extfile openssl.cnf -extensions req_ext -days 500 -sha256
 cp nginx.cnf /etc/nginx/sites-enabled/$APP
-echo "$DNS" | tee -a /etc/bind/named.conf.local
+if ! grep -qF "$DNS" /etc/bind/named.conf.local; then
+    echo "$DNS" | tee -a /etc/bind/named.conf.local
+else
+    echo "Entry already exists in named.conf.local"
+fi
 cp zonefile.cnf /etc/bind/db.$DOMAIN
 docker run -p $PORT:5000 --name $APP --restart always -d $APP