[dns-operations] Oddness with Cloudfare authoritative servers

Adam David adam.vallee at gmail.com
Wed Sep 22 23:16:59 UTC 2021

This does not seem to be a DNS resolution/misconfiguration issue on
Cloudflare's end. provides an error message (as it should) indicating it
is a CloudFlare IP. If you can't see that in a web browser, then the issue
is local to your network.

The main causes that I gather would be:

1. There was a temporary cache propagation issue on CF's network. (Still
not a DNS issue.)
2. Your IT department is using or possibly even
where they intended to use (RFC1918 IP space). This would
block access to the netblock belonging to Cloudflare and you would have
difficulty accessing thousands of websites.
                                 Side Note: belongs
to AS13335.

You should always start with your IT department.
If you are a Cloudflare customer, contact them directly.
If you are a DeltaMath customer, then you need to contact them directly.


Adam Vallee

On Wed, Sep 22, 2021 at 4:03 PM Brown, William <wbrown at e1b.org> wrote:

> From: dns-operations <dns-operations-bounces at dns-oarc.net> On Behalf Of
> Erik Stian Tefre
> Sent: Wednesday, September 22, 2021 3:38 PM
> To: dns-operations at lists.dns-oarc.net
> Subject: Re: [dns-operations] Oddness with Cloudfare authoritative servers
> > Possibly not a DNS issue at all, but something like this:
> > https://community.cloudflare.com/t/revil-ransomware/301435
> > (Executive summary: One Cloudflare IP being blocked by a firewall
> because of a different and misbehaving Cloudflare customer who happened to
> serve malicious content from that same IP.)
> > Regards,
> > Erik
> Interesting.  The real issue I am experiencing is that I am getting
> inconsistent responses from nominally the same authoritative server.  It
> just so happens that when we get as the answer it fails.  I
> would prefer to get the correct answer so students can use the online
> educational resource the district is paying for.
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