Re:Google Public DNS turns 8.8.8.8 years old
by Dylan16807 on Tuesday August 14, 2018 @03:02AM
(#17756045)
> What is this system that prevents pattern-of-life analysis while still sending all DNS queries to one nameserver?
Setting $CACHE_TTL to "months" on everything, and doing nothing else.
> I'm still sending frequent short-TTL (normal caching) DNS lookups for most hosts that would betray my pattern-of-life in aggregate.
Your system does that. This theoretical mildly-inferior system would not have frequent DNS lookups for any record type.
Re:Google Public DNS turns 8.8.8.8 years old
by pdkl95 on Tuesday August 14, 2018 @04:02AM
(#17756235)
> Setting $CACHE_TTL to "months" on everything, and doing nothing else.
That will break a lot.
DNS isn't static; IPs regularly change as servers move, CDNs are introduced/changed. Long-term caching only works on NS records because changing DNS delegations is relatively rare. NS record caching does cause problems, but they are infrequent. Caching the addresses of the actual servers will break some things within days, and most of the internet the next time each server is updated/moved/etc.
Aggressive caching of NS records for TLDs doesn't do anything to prevent a single upstream nameserver from leaning your pattern of life from the frequent DNS lookups for A records that are not cached longer than normal.