DNS DOS increasing?

Miquel van Smoorenburg miquels at cistron.nl
Mon Jan 21 17:58:03 UTC 2002

In article <cistron.171DAAD54475984F8F41345A0945DF9C39ED49 at hqexchange.presidio.com>,
James Smith  <jsmith at PRESIDIO.com> wrote:
>  Get ready for more DOS-like behavior as systems get deployed that have 10
>second TTLs in the DNS. These systems are used to provide multi-isp
>redundancy by pinging each upstreams router, and when a ping fails, start
>giving out a dns response using the other ISP IP range. Same FQDN, new IP.

So what we need is a tunable on the caching DNS server that says

min_allowed_ttl = 300;

if (ttl < min_allowed_ttl) ttl = min_allowed_ttl;

If the above becomes a problem, this will happen.


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