Step 4: Modify the DNS Records of the Domain Name

Prerequisites

• You have added the domain name you want to protect to the cloud WAF instance you have in CNAME access mode. For details, see Step 1: Add a Domain Name to WAF (Cloud Mode).
• You have the permission to modify domain name resolution settings on the DNS platform hosting your domain name.
• You have whitelisted WAF back-to-source IP addresses on your origin servers.
• (Optional) You have tested your website connectivity to ensure that WAF can forward requests.

How WAF Works

• No proxies used

  DNS resolves your domain name to the origin server IP address before the website is connected to WAF. DNS resolves your domain name to the CNAME of WAF after the website is connected to WAF. Then WAF inspects the incoming traffic and filters out malicious traffic.

• A proxy (such as anti-DDoS service) used

  If a proxy such as anti-DDoS service is used on your website before it is connected to WAF, DNS resolves the website domain name to the anti-DDoS IP address. The traffic goes to the anti-DDoS service and the anti-DDoS service then routes the traffic back to the origin server. After you connect your website to WAF, change the back-to-source address of the proxy (such as anti-DDoS service) to the CNAME of WAF. In this way, the proxy forwards the traffic to WAF. WAF then filters out illegitimate traffic and only routes legitimate traffic back to the origin server.

  Note

  • To ensure that WAF can properly forward requests, test WAF by referring to Testing WAF before modifying the DNS configuration.
  • To prevent other users from configuring your domain name on WAF before you add it to WAF (this will cause interference on your domain name protection), add the subdomain name and TXT record on your DNS management platform. WAF will determine which user owns the domain name based on the subdomain name and TXT record.

Procedure

1. Log in to the management console.
2. Click in the upper left corner of the management console and select a region or project.
3. Click in the upper left corner and choose Security > Web Application Firewall.
4. In the navigation pane on the left, choose Website Settings.
5. Obtain the CNAME record of WAF.
   • Method 1: After Step 3: Test WAF is complete, expand Step 3: Change DNS Resolution, and copy the CNAME record on the displayed page. Alternatively, go to the Website Settings page, locate the target domain name, and click Modify DNS in the Access Status column. Then, copy the CNAME record on the page displayed.
   • Method 2: On the Website Settings page, click the domain name to go to its basic information page. In the CNAME row, click to copy the CNAME record.

6. Connect the domain name to WAF.
   • No proxy used

     Configure the CNAME record at your DNS provider. For details, contact your DNS provider.

   • Proxy used

     Change the back-to-source IP address of the used proxy, such as anti-DDoS and CDN services, to the copied CNAME record.

     Note

     To prevent other users from configuring your domain names on WAF in advance (this will cause interference on your domain name protection), add the subdomain name and TXT record on your DNS management platform.

     1. Obtain Subdomain Name and TXT Record: In the row of Access Status, click How to Access. In the Access Guide dialog box, copy Subdomain Name and TXT Record.
     2. Add Subdomain Name at the DNS provider and configure TXT Record for the subdomain name.

     WAF determines which user owns the domain name based on the configured Subdomain Name and TXT Record.

7. Verify that the CNAME of the domain name has been configured.
   1. In Windows, choose Start > Run. Then enter cmd and press Enter.
   2. Run a nslookup command to query the CNAME record.

      If the configured CNAME is returned, the configuration is successful.

      Example command:

      nslookup www.example.com
      
      

8. After the preceding steps are complete, select Finished.