Resolver behavior on expired TTLs

[John Miller]

Thanks, Matus.  Much appreciated--a SERVFAIL is much better than an 
NXDOMAIN in this scenario.

John


On 02/21/2013 10:41 AM, Matus UHLAR - fantomas wrote:
> On 21.02.13 10:38, John Miller wrote:
>> Here's something I hadn't put much thought into until recently--it's
>> never been a problem--how do resolvers behave when they receive a
>> request for an expired entry in the cache, but cannot contact the
>> authoritative nameserver?  I'd imagine they return a SERVFAIL, but I
>> could see NXDOMAIN as well.  Does anyone know the answer?
>
> they should not sent anything but SERVFAIL if they are unable to do the
> resolution. SERVFAIL should cause the client ask other server, while
> NXDOMAIN means that the host does not exist and client can stop searching.
>