Google Public DNS resolve Google.com and YouTube.com issue

Bowie Chan

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Jun 1, 2022, 12:31:29 PM6/1/22

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I just advertised a /24 subnet via AS3491.

As checked, the IP geo information should be in Hong Kong.

When setting a Hong Kong local DNS, the resolve of Google.com and YouTube.com is normal with RTT ~10ms.

However, when setting 8.8.8.8 as DNS, the RTT to Google.com and YouTube.com is over 200ms. Other website is normal.

Anyway to resolve this? What's the root cause.

Bowie

Tianhao Chi

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Jun 1, 2022, 12:37:24 PM6/1/22

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What is your client subnet? What IP did it resolve to for google.com and youtube.com? And is it different from what your local resolver gave you?

Floris

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Jun 1, 2022, 5:53:31 PM6/1/22

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Is it 154.208.136.0/24 by any chance? This (only) subnet was announced in the past week for AS3491. I see multiple locations for this IP from different geo providers: Hong Kong, Seychelles and the Netherlands. You are probably being routed to the wrong datacenter due to ECS.

Using the above subnet I indeed see that you would be returned a Google server's IP address from the Netherlands, far away from Hong Kong.

$ dig google.com +short +subnet=154.208.136.0/24 @8.8.8.8
142.251.36.46

$ host 142.251.36.46
46.36.251.142.in-addr.arpa domain name pointer ams17s12-in-f14.1e100.net.

Tianhao Chi

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Jun 2, 2022, 3:13:04 PM6/2/22

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Does other resolvers give different answer that's near Hongkong and what did you see?

Claus Mattsson

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Jun 3, 2022, 9:03:47 AM6/3/22

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You may do that investigation yourself by applying use of dig and host tool as described above.

Ahmed Bek

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Jun 21, 2022, 2:15:06 PM6/21/22

to Tianhao Chi, public-dns-discuss

From: 'Tianhao Chi' via public-dns-discuss <public-dn...@googlegroups.com>
Sent: Thursday, June 2, 2022 9:13:04 PM
To: public-dns-discuss <public-dn...@googlegroups.com>
Subject: [public-dns-discuss] Re: Google Public DNS resolve Google.com and YouTube.com issue

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