[dns-operations] Capturing Traffic

Robert Edmonds edmonds at isc.org
Mon Feb 25 18:04:05 UTC 2013

Lyle Giese wrote:
> I would check to see what happens to domains that don't exist.  Esp
> asking for the MX records for a domain that doesn't exist.
> I had heard stories that some public resolvers will resolve when
> they should not.  For surfing, minor issue.  For a mail server,
> major issue.

apparently google heard those stories too.


    How is Google Public DNS different from my ISP's DNS service or
    other open DNS resolvers? How can I tell if it is better?

        [...] Unlike Google Public DNS, some ISPs and open resolvers
        block, filter, or redirect DNS responses.

    How does Google Public DNS handle non-existent domains?

        If you issue a query for a domain name that does not exist,
        Google Public DNS always returns an NXDOMAIN record, as per the
        DNS protocol standards. The browser should show this response as
        a DNS error. [...]

Robert Edmonds
edmonds at isc.org

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