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I am trying to learn/experiment with some networking basics. I am on macOS with DHCP configured. I purposely removed the default gateway IP address (192.168.0.1) by going to the networking settings. I also confirmed there is no default route by running:

route get default
route: writing to routing socket: not in table

I can access Google Search and YouTube, but I can't access some other sites like superuser.com. What's going on?

Peter Mortensen
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java_doctor_101
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1 Answers1

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You have only disabled IPv4 by deleting the IPv4 default gateway.
You have not disabled IPv6.

You are using IPv6 to get to IPv6-capable sites.

SuperUser.com, surprisingly, does not appear to be IPv6-enabled yet, which is why you can't get to it. Google's properties, including YouTube, are usually IPv6-enabled.

Spiff
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    "SuperUser.com, surprisingly, does not appear to be IPv6-enabled" Adding Internet-facing IPv6 support for web applications can be onerous and rewards such effort with a zero-to-negative ROI. But the answer to the OP's question I think is sound and probably correct. – hemp Jun 07 '21 at 18:39
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    @hemp how is supporting IPv6 onerous, mostly I have encountered resistance at consumer ISPs that have a large deployment of legacy hardware. Hosting providers almost always have IPv6 by default. – r_ahlskog Jun 08 '21 at 09:41
  • @r_ahlskog larger attack surface, I guess. – Dan M. Jun 08 '21 at 15:05
  • @DanM. fair, but today I see the reverse all the SSH bots and poorly configured PHP exploits are hitting the IPv4 address. – r_ahlskog Jun 08 '21 at 15:54
  • @r_ahlskog for simple web pages, yes, many hosting providers enable IPv6 by default. Web applications are a different story. Microservices sitting behind WAFs and using load balancers make everything more complex and adding DNS entries for IPv6 addresses requires duplication of everything. In short, it's more work and offers no benefits, so it doesn't happen. It really doesn't need to either. Once IoT devices _don't use_ IPv4, there will plenty of address space for web sites and apps. – hemp Jun 10 '21 at 17:19