diff --git a/README.md b/README.md
index b6c54c0..8893f8e 100644
--- a/README.md
+++ b/README.md
@@ -81,7 +81,7 @@ ssl_key_file = "/etc/ddns-service/key.pem"  # required if ssl = true
 path = "/var/lib/ddns-service/ddns.db"  # required for sqlite
 
 [dns_service]
-# dns_server = "localhost"  # default: "localhost" (DNS server for RFC 2136 updates)
+# dns_server = "127.0.0.1"  # default: "127.0.0.1" (must be IP address)
 # dns_port = 53  # default: 53
 # dns_timeout = 5  # default: 5 (seconds)
 # ddns_default_key_file = "/etc/ddns-service/ddns.key"  # optional, BIND TSIG key file
diff --git a/files/config.example.toml b/files/config.example.toml
index 2d718a6..04cdd2e 100644
--- a/files/config.example.toml
+++ b/files/config.example.toml
@@ -25,7 +25,7 @@ path = "/var/lib/ddns-service/ddns.db"  # required for sqlite
 # database = "ddns"  # required for mariadb
 
 [dns_service]
-# dns_server = "localhost"  # default
+# dns_server = "127.0.0.1"  # default, must be IP address
 # dns_port = 53  # default
 # dns_timeout = 5  # default, seconds
 # ddns_default_key_file = "/etc/ddns-service/ddns.key"  # optional, BIND TSIG key
diff --git a/src/ddns_service/config.py b/src/ddns_service/config.py
index 0b91539..2c96207 100644
--- a/src/ddns_service/config.py
+++ b/src/ddns_service/config.py
@@ -145,7 +145,7 @@ def load_config(config_path):
     cfg["database"].setdefault("backend", "sqlite")
 
     cfg.setdefault("dns_service", {})
-    cfg["dns_service"].setdefault("dns_server", "localhost")
+    cfg["dns_service"].setdefault("dns_server", "127.0.0.1")
     cfg["dns_service"].setdefault("dns_port", 53)
     cfg["dns_service"].setdefault("dns_timeout", 5)
     cfg["dns_service"].setdefault("cleanup_interval", 60)
diff --git a/src/ddns_service/models.py b/src/ddns_service/models.py
index 16d333a..50878c9 100644
--- a/src/ddns_service/models.py
+++ b/src/ddns_service/models.py
@@ -81,7 +81,7 @@ def init_database(config: dict):
         logging.info(f"Database backend: SQLite path={db_path}")
 
     elif backend == "mariadb":
-        new_db = MySQLDatabase(
+        db = MySQLDatabase(
             config["database"]["database"],
             host=config["database"].get("host", "localhost"),
             port=config["database"].get("port", 3306),
@@ -89,10 +89,8 @@ def init_database(config: dict):
             password=config["database"]["password"],
         )
         # Re-bind models to new database
-        User._meta.database = new_db
-        Hostname._meta.database = new_db
-        # Replace global db reference
-        db = new_db
+        User._meta.database = db
+        Hostname._meta.database = db
         logging.info(f"Database backend: MariaDB db={config['database']['database']}")
 
     else: