[plug] Flushing DNS cache

[Daniel Pittman]

Jason Posavec <jasonposavec at iinet.net.au> writes:

> Can anybody help with an appropriate command to flush my ISP's DNS cache
> when a particular website has changed its server details?

You can't flush the ISP DNS cache, only one that you control.  (Imagine if you
could: anyone in the universe[1] could flush the DNS cache, costing you more
money /and/ making you more vulnerable to attacks!)

> The Ubuntu forums have been less than helpful with "flush DNS
> cache". Apparently the equivalent Windoze command would be ipconfig
> /flushdns.

Linux doesn't cache by default, but various add-ons can.

If you have nscd installed, it has a command line option to flush the cache.

If you use recent bind then 'rndc flush' will do it.


> And yes, if somebody was to have a guess at why I want this they'd probably
> be right... ;)

...however, if your browser is doing the wrong thing, restart it.  All the
browsers have their own internal cache of DNS names that they hold on to for
grim death in an effort to save us from security risks.[2]

Given that the *only* way to flush *their* cache is to restart the browser.

        Daniel

Footnotes: 
[1]  ...or, even just in the subscriber base, which is identical if any one of
     their machines is taken over.

[2]  ...and, yes, I /am/ bitter about this, and it /is/ because I get bitten
     by it because I use a laptop that crosses a split-view DNS boundary on
     occasion.

-- 
✣ Daniel Pittman            ✉ daniel at rimspace.net            ☎ +61 401 155 707
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