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0 pointsxorcist9y ago0 comments

It's called the resolver cache, and Linux does it too. Most commonly with nscd (use "nscd -i hosts" to clear it, keep in mind this is not specific to DNS requests). In the specific situation of a web browser it's more complicated and you'll find that the web browser caches these things too. If you run Chrome check out chrome://net-internals to get a glimpse of what's going on there.

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Declanomous9y ago· 1 in thread

Thanks for the tip on net-internals. I think I used a similar feature in Firefox a long time ago, but I've never used this tool in Chrome before.

I know Chrome in Linux definitely doesn't cache DNS requests. I believe Linux only keeps the DNS info around until the socket closes, but I don't know the actual implementation. I looked in to the ncsd man page, and it looks like DNS info isn't cached, only open sockets.

I know Chrome uses the system DNS cache in Windows, and my understanding was that all browsers in Windows used the system DNS cache.

I don't know a lot about how sockets are handled. I thought they were discarded as soon as they were closed, but they could function similarly to a DNS cache. I though a DNS cache stuck around for a lot longer though.

ChoGGi9y ago

I have the DNS cache service on Windows 7 disabled, and Chrome still caches DNS requests.

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