Alibaba Cloud DNS:CNAME record resolution optimization

Background

To provide a better intelligent resolution experience, Alibaba Cloud DNS optimized the CNAME record resolution logic on May 31, 2019. This optimization prevents CNAME records from interfering with the priority matching of intelligent resolution lines.

Adjustment method

Scenario 1: www.dns-example.com Overseas: A record "1.1.X.X" Default: CNAME record "www.aliyun.com"

User query	Previous behavior	New behavior
Domestic users query A record	CNAME record "www.aliyun.com"	CNAME record "www.aliyun.com"
Overseas users query A record	A record "1.1.X.X"	A record "1.1.X.X"
Domestic users query AAAA record	CNAME record "www.aliyun.com"	CNAME record "www.aliyun.com"
Overseas users query AAAA record	Responds with CNAME record "www.aliyun.com"	Does not respond with CNAME record "www.aliyun.com"

Scenario 2: www.dns-example.com Overseas: AAAA record "2400:3200:2000:10::1" Default: CNAME record "www.aliyun.com"

User query	Previous behavior	New behavior
Domestic users query A record	CNAME record "www.aliyun.com"	CNAME record "www.aliyun.com"
Overseas users query A record	Responds with CNAME record "www.aliyun.com"	Does not respond with CNAME record "www.aliyun.com"
Domestic users query AAAA record	CNAME record "www.aliyun.com"	CNAME record "www.aliyun.com"
Overseas users query AAAA record	AAAA record "2400:3200:2000:10::1"	AAAA record "2400:3200:2000:10::1"

Compatible configuration

After this optimization, if a CNAME record exists in the default line and only an AAAA record is added to the overseas line, overseas users querying the domain cannot access the IPv4 address of the CNAME target domain. To allow overseas users to still access the IPv4 address, add an A record under the overseas line. For example:

www.dns-example.com Overseas: AAAA record "2400:3200:2000:10::1", A record "1.1.X.X" Default: CNAME record "www.aliyun.com"