:Cache-accelerated Domain Name

Benefits

• Distributed denial of service (DDoS) attack mitigation: DNS responses are cached to protect your authoritative DNS servers from DDoS attacks and reduce the loads on your authoritative DNS servers.

• DNS access acceleration: Alibaba Cloud DNS provides global nodes. This allows you to access the nearest node and increases the access speed.

• Backup for DNS servers: If an error occurs in your authoritative DNS server, the Cache-accelerated Domain Name service allows you to use the service before the cached DNS records expire. This shortens the time wasted by the error.

• Cost-effectiveness: If you use on-premises DNS servers, the Cache-accelerated Domain Name service can help you reduce bandwidth usage to save costs.

Terms

1. Cache-accelerated Domain Name

   The domain name for which you want to activate the Cache-accelerated Domain Name service. It only can be a primary domain name.

2. Origin DNS Servers

   The addresses and ports of authoritative DNS servers. If the address of an authoritative DNS server is ns1.alidns.com, ns1.alidns.com:53 is displayed in the Origin DNS Servers column.

3. Alibaba Cloud DNS Access Status

   Status	Description	Cause	Solution
   Normal	The domain name is registered with Alibaba Cloud DNS.	The domain name is bound to the DNS server assigned by Alibaba Cloud DNS.	Normal. No operations are required.
   Not Use Alibaba Cloud DNS	The domain name is not bound to the DNS server assigned by Alibaba Cloud DNS, leading to invalid cache-accelerated domain name resolution.	The domain name is not hosted by the DNS server assigned by Alibaba Cloud DNS. Note DNS servers configured for the Cache-accelerated domain name: cache1.alidns.com and cache2.alidns.com.	Go to the website of your domain name registrar to change the DNS servers, and bind the domain name to at least one DNS server assigned by Alibaba Cloud DN. For more information, see Change DNS server. Note You can keep the original DNS server based on your business requirements.
   		No DNS server is configured for the domain name.	Change the IP address of the DNS sever to the IP address of the DNS server assigned by Alibaba Cloud DNS. For more information, see Change DNS server.

Limits

1. If Alibaba Cloud DNS is applied to both a primary domain name and a subdomain name, you cannot use the Cache-accelerated Domain Name service for the subdomain name.

2. You cannot configure intelligent DNS resolution for the Cache-accelerated Domain Name service.

3. You cannot configure DNSSEC for the Cache-accelerated Domain Name service.

Procedure

1. Log on to the Alibaba Cloud DNS console.

2. In the left-side navigation pane, click Authoritative Domain Name. On the Authoritative Domain Name page, click the Cache-accelerated Domain Names tab.

3. Click Create Cache-accelerated Domain Name and set the required parameters.

   You must set the following parameters:

   Cache-accelerated Domain Name: the domain name for which you want to activate the Cache-accelerated Domain Name service.

   Service Instance: the instance that you want to bind. You can select a Cache-accelerated Domain Name instance that you have purchased from the drop-down list. If no instance is displayed in the drop-down list, click here to buy one.

   Minimum TTL Period of Back-to-origin Cached Data and Maximum TTL Period of Back-to-origin Cached Data: the minimum and maximum time-to-live (TTL) periods. During the TTL periods, the DNS records of the domain name for which you want to activate the Cache-accelerated Domain Name service are effective. Unit: second. Valid values: 30 to 86400.

   Note

   After the Cache-accelerated Domain Name service is activated, the TTL period of the local DNS is subject to the TTL period specified when you activate the Cache-accelerated Domain Name service. If an Internet service provider (ISP) extends the TTL period, contact the ISP to resolve the issue.

   Back-to-origin DNS Query Protocol: Resolution requests are sent to authoritative DNS servers over UDP. Only UDP is supported.

   Support for EDNS Client Subnet on Origin DNS Servers: You can select this check box if your authoritative DNS servers support the Extension Mechanisms for DNS (EDNS) protocol. Assume that the local DNS also supports the EDNS protocol. When the local DNS sends a recursive resolution request, the Cache-accelerated Domain Name service sends the egress IP address of the client contained in the resolution request to your origin DNS server.

   Origin DNS Servers: You can specify one or more origin DNS servers. The default port is 53. You can specify the actual ports of the origin DNS servers.