Overview

You can connect to an RDS for SQL Server instance using the SQL Server Management Studio client or Data Admin Service (DAS).

**Table 1** Connection methods
Connection Method	Connection Address	Description
(Recommended) Connect to an RDS for SQL Server instance through DAS	Not required	DAS enables you to manage databases on a web-based console. It supports SQL execution, advanced database management, and intelligent O&M, simplifying database management and improving both efficiency and data security. The permissions required for connecting to DB instances through DAS are enabled by default.
Connect to an RDS for SQL Server instance through the SQL Server Management Studio client	For details, see Connecting to a DB Instance over a Private or Public Network Using a CLI.	You can use SQL Server Management Studio to connect to a DB instance through a non-SSL connection or an SSL connection. The SSL connection encrypts data and is more secure.

Table 2 lists how to use a CLI to connect to an RDS for SQL Server instance over a private or public network.

Figure 1 Connecting to a DB instance over a private or public network

**Table 2** Connecting to a DB instance over a private or public network
Connection Method	IP Address	Security Group Rules	Description
Private network	Floating IP address	If the ECS and RDS DB instance are in the same security group, they can communicate with each other over a private network by default. No security group rules need to be configured. If they are in different security groups, configure security group rules for them, separately. RDS DB instance: Configure an inbound rule for the security group with which the RDS DB instance is associated. For details, see Configuring Security Group Rules. ECS: The default security group rule allows all outgoing data packets. In this case, you do not need to configure a security group rule for the ECS. If not all outbound traffic is allowed in the security group, you need to configure an outbound rule for the ECS.	Secure and high-performance Recommended
Public network	You need to purchase an EIP. For pricing details, see EIP Billing.	To access a DB instance from resources outside the security group that the DB instance is associated with, you need to configure an inbound rule for the security group. For details, see Configuring Security Group Rules.	Less secure To achieve a higher transmission rate and security level, you are advised to migrate your applications to an ECS that is in the same VPC as your RDS DB instance and use a floating IP address to access the DB instance.