bind-9.7.2 not forward CNAMEDed domain names

[Drunkard Zhang]

I just add these in default named.conf:

zone "speedtest.360.cn" {
        type forward;
        forwarders { 211.161.192.1; };
};

which reacts like this:

17:20:09 ~ $ dig +nocmd speedtest.360.cn @211.161.192.146 +multiline
+noall +answer
speedtest.360.cn.	34 IN CNAME speedtest.360.cn.cloudcdn.net.
speedtest.360.cn.cloudcdn.net. 82 IN CNAME cloud010005.cachecn.com.
cloud010005.cachecn.com. 526 IN	A 112.90.216.14

But, it should be like below:

17:20:24 ~ $ dig +nocmd speedtest.360.cn @211.161.192.1 +multiline
+noall +answer
speedtest.360.cn.	1176 IN	CNAME speedtest.360.cn.cloudcdn.net.
speedtest.360.cn.cloudcdn.net. 19 IN CNAME cloud010005.cachecn.com.
cloud010005.cachecn.com. 232 IN	A 61.155.141.28

The upstream DNS server 211.161.192.1 did responsed correctly, by
analysis via tcpdump.
But why bind didn't use THE RESPONSE, but resolves again from root-servers.

To get what I want, I have to add cloud010005.cachecn.com too...
zone "speedtest.360.cn" {
        type forward;
        forwarders { 211.161.192.1; };
};
zone "cloud010005.cachecn.com" {
        type forward;
        forwarders { 211.161.192.1; };
};

Any tips?
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