Firewall unable to resolve Private IP - DNS Translation

I have FG-80F (Firmware version 7.2.4 build1396) in one of the branch office which we have recently purchased and configured. I have configured DNS translation as follows and internal hosts behind this firewall is able to resolve to the Private IP 172.24.0.1 as expected. However, when I try ping or configure the hostname (testing.abc.com) in the Threatfeeds configuration, it resolves to Public IP address 181.182.183.184. I have FG-500D (Firmware version 6.4.11 build2030) and that firewall is able to resolve with the private IP. Anything that I am missing here?

config firewall dnstranslation
edit 1
set src 181.182.183.184 --> Public IP as an example for "testing.abc.com"
set dst 172.24.0.1 --> Private IP of testing.abc.com

end

hostname - "testing.abc.com"

PS : Hostname & Public IP address are just an example and not actuals.