MacOS – Ping cannot resolve .io domains yet nslookup can

dnsmacos

macOS 10.12.1 (16B2555) on an early 2015 Macbook Pro.

I can't resolve any .io domains on this machine. Other people on the same network can. This happens here at the office, and at home.

I've tried different browsers, I've turned it off and on again.

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[~]$ nslookup ngrok.io
Server:     10.15.0.1
Address:    10.15.0.1#53

Non-authoritative answer:
Name:   ngrok.io
Address: 52.25.124.181
Name:   ngrok.io
Address: 52.41.214.241
Name:   ngrok.io
Address: 54.68.226.153

[~]$ ping ngrok.io
ping: cannot resolve ngrok.io: Unknown host

If I add the domain manually to /etc/hosts, and then run a traceroute, I don't see anything abnormal. I'm able to bring up the domain in a browser.

Definitely seems like a DNS issue, however, I'm not using DNS settings that are any different from anyone else on either my home or work network.

If I change the DNS servers manually to 8.8.8.8, it STILL does not work.

Best Answer

You may have been impacted by recent issues of a portion of the .io TLD Nameservers delivering NXDOMAIN responses which then cascaded throughout all DNS entries globally.

Only a portion of the nameservers were doing this, leading to discrepancies in the cached values downstream, which in turn lead to intermittent failure to lookup the host server when making requests.

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