Unable to download Threat Protection Ruleset

[#1]

Hello There,

I'm Unable to download Threat Protection Rulesets,throws me below error

Seems like ts.infoblox.com is down or unreachable, can anyone help me with this?

Also,  not able to ping "ts.infoblox.com" from other networks as well & request gets time out.

Any Insights would be helpful,

Thanks! 

[#2]

Have you configure dns resolver on grid master and make sure that grid master has access to internet?

From the error seems like the grid master not able to resolve ts.infoblox.com

[#3]

We ran into same issue after upgrade from 8.4.4 to 8.6.1.  DNS resolver set to 127.0.0.1, probably default for the Grid.  It worked before the upgrade without a DNS resolver other than 127.0.0.1 but now does not work.  We will specify the DNS resolver now.