On 06.12.13 15:52, sumsum 2000 wrote:
I am having only a forward only option in bind configuration.
When i dig on some host which has CNAME, the cache contains a longer TTL
for the CNAME than the TTL for the final resolution of the IP.
Yes, every record has its own TTL, including every record in CNAME chain.
However, in the example below, the CNAME is queried again when the TTL
for a336.g.akamai.net. is up.
Pardon?
I was expecting that the TTL for CNAME will be used from the cache and the
lookup will not happen again until the TTL has not expired.
When a name is queried, query is processed always the same way - every name
of a chain is validated again and missing/expired names are resolved again.
Note that records can removed from memory even without expiring, e.g. when
memory is full.
Is there a way to avoid additional lookups when the value is already
present in the cache for CNAME entries.
not without violating DNS standard.
;; ANSWER SECTION:
emp.bbci.co.uk. 436 IN CNAME emp-live.bbc.net.uk.
emp-live.bbc.net.uk. 253 IN CNAME emp.bbci.co.uk.edgesuite.net.
emp.bbci.co.uk.edgesuite.net. 3368 IN CNAME a336.g.akamai.net.
a336.g.akamai.net. 6 IN A 58.27.124.225
a336.g.akamai.net. 6 IN A 58.27.124.200
--
Matus UHLAR - fantomas, uh...@fantomas.sk ; http://www.fantomas.sk/
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Varovanie: na tuto adresu chcem NEDOSTAVAT akukolvek reklamnu postu.
Quantum mechanics: The dreams stuff is made of.
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