Does browser cache easily cirmcumvent OpenDNS

Comments

3 comments

  • Avatar
    rotblitz

    With the caches nothing is circumvented, but the content which you visited before is presented again.  This is how the web works unless you disable the cache on the browsers and on the OS which you can do.  Because of your local caches, OpenDNS is not designed for frequent settings changes.

    "The idea is that when I want my child to focus on homework I switch to Whitelist Only mode."

    A bad idea.  This is not how it is supposed to work.

    "Or if I want to disable the internet I would block everything."

    Another bad idea.  DNS (and therefore OpenDNS) cannot control your internet connection.  Only your router may be able to do this.

    "But in order to this to take effect, do I need to ask my child to also flush their DNS cache and clear his browser cache every time?"

    If you want your settings changes to take effect immediately , then yes, the caches must be cleared.  Else the settings changes will take effect delayed, depending on when the caches for a certain entry expire.

    Btw, beside disabling the caches you can also run a scheduled task on computers to automatically flush the caches in certain time intervals.  But you would still need to make the dashboard settings changes manually.

    So yes, the way you want to use this and given these technical facts "render the tool useless" for you, not for anybody else.

    0
    Comment actions Permalink
  • Avatar
    andrewscott (Edited )

    That is correct - it renders the tool useless as a parental control tool for me personally. I disabled DNS cache on my son's computer and OpenDNS is still hit-and-miss on what it blocks, even for domains I explicitly block.

    Worse, changes to filtering take several hours, not several minutes, to take effect. There's no scenario where I want to change the filtering mode at some non-specific point several hours in the future.

    It seems that the tool is useful if you want to stick to one filtering level and set of allowed/blocked domains without changing it. That is a valid scenario, and in that case even the hours-long delay and browser cache aren't a real problem.

    But wanting to make an occasional change from more restrictive to less restrictive or vice versa is also a valid scenario. Given that changes supposedly take effect in three minutes, it's reasonable to conclude that one could make changes and have them take effect in that time frame, at least on the DNS side. If that's a "bad idea" or "not how it's supposed to work" then I'd call it poor communication. I won't call it misleading because that's too accusatory and I don't see any intent to deceive.

     

    0
    Comment actions Permalink
  • Avatar
    rotblitz

    " I disabled DNS cache on my son's computer and OpenDNS is still hit-and-miss on what it blocks"

    Yes, because the browser cache (temporary internet files) is the other culprit which must be flushed.

    "Worse, changes to filtering take several hours, not several minutes, to take effect"

    You lucky guy!  I have seen occurrences where browser caches served outdated content still after months!  And the DNS cache (local resolver cache) can remain for up to 72 hours, depending on the TTLs set for specific domains, or until the computer is rebooted.

    "It seems that the tool is useful if you want to stick to one filtering level and set of allowed/blocked domains without changing it."

    Correct, you got it!

    "But wanting to make an occasional change from more restrictive to less restrictive or vice versa is also a valid scenario."

    Fully agreed.  And therefore there are these Netgear routers with Live Parental Controls powered by OpenDNS where you can easily facilitate scheduled filtering as well.
    See https://www.netgear.com/lpc and https://kb.netgear.com/25687/

    But as you do not seem to have a Netgear router, I didn't point this option out earlier...

    0
    Comment actions Permalink

Please sign in to leave a comment.