[AusNOG] Anyone else notice the click frenzy traffic

[Mark Andrews]

In message <50ACC2B2.2050404 at visser.name>, Jeremy Visser writes:
> On 21/11/2012 11:00, Chris Jones wrote:
> > Because most CDNs use DNS-based GSLB  - via a CNAME record - and you
> > can't have a CNAME for the Apex (root) of the domain.
> 
> What would be the real-world implications of actually serving a CNAME at 
> the root?

You get inconsistent answers depending apon what records are loaded
into the cache and in what order they are learnt.  This is documented
in RFC 1034.

3.6.2. Aliases and canonical names

The domain system provides such a feature using the canonical name
(CNAME) RR.  A CNAME RR identifies its owner name as an alias, and
specifies the corresponding canonical name in the RDATA section of the
RR.  If a CNAME RR is present at a node, no other data should be
present; this ensures that the data for a canonical name and its aliases
cannot be different.  This rule also insures that a cached CNAME can be
used without checking with an authoritative server for other RR types.

Mark

> I know that Microsoft's DNS server lets you do it, for 
> example. It "works", using the "I haven't seen what it breaks" sense of 
> the word.
> 
> (One of these days we'll be resolving web servers with SRV records, but 
> until then...)
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-- 
Mark Andrews, ISC
1 Seymour St., Dundas Valley, NSW 2117, Australia
PHONE: +61 2 9871 4742                 INTERNET: marka at isc.org