[dns-operations] Large amount of TXT records on cisco.com causing truncation

[Nicolas Baumgarten]

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On Wed, Mar 6, 2024 at 6:55 PM Dan McCombs via dns-operations <
dns-operations at dns-oarc.net> wrote:

>
>
>
> ---------- Forwarded message ----------
> From: Dan McCombs <dmccombs at digitalocean.com>
> To: dns-operations at lists.dns-oarc.net
> Cc:
> Bcc:
> Date: Wed, 6 Mar 2024 16:50:31 -0500
> Subject: Large amount of TXT records on cisco.com causing truncation
> Hi all,
>
> Is there anyone from Cisco on this mailing list?
>
> I was looking through some queries earlier and noticed a large amount of
> cache misses on our infra for TXT queries for cisco.com. There's a lot of
> TXT records there that look like a lot of possibly stale site/domain
> verification entries, and I'm wondering if those could be cleaned up to
> save the extra queries hitting your nameservers.
>
> The cisco.com nameservers are responding with the TC flag set and no
> answer, so clients querying via UDP keep missing cache before retrying over
> TCP. It receives a fair amount of traffic with a lot of unnecessary UDP
> queries because of that. I added a rule to dnsdist to respond with TC
> directly for now in that case, but I'm sure it would help both themselves
> and others to clean up those records since it's a popular domain.
>
> Take care,
>
> -Dan
>
>
> Dan McCombs
> Senior Engineer I - DNS
> dmccombs at digitalocean.com
>
>
>
> ---------- Forwarded message ----------
> From: Dan McCombs via dns-operations <dns-operations at dns-oarc.net>
> To: dns-operations at lists.dns-oarc.net
> Cc:
> Bcc:
> Date: Wed, 6 Mar 2024 16:50:31 -0500
> Subject: [dns-operations] Large amount of TXT records on cisco.com
> causing truncation
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