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I've been making some updates to DNS records of a website that I administrate. Call it example.com.

Running host example.com returns Host example.com not found: 3(NXDOMAIN). Naturally, ping, curl, and visiting the site in a browser also fail.

However, if I ssh to a different machine, all of these work as expected. My conclusion: My DNS is messed up.

To solve that, I tried dscacheutil -flushcache (both with and without sudo), and also tried sudo killall -HUP mDNSResponder, the flushing command new to Lion & Mtn Lion.

I confirmed with tail -f /var/log/system.log that the killall command purged the cache:

Nov 22 02:20:49 xxxxxxxxx mDNSResponder[12]: SIGHUP: Purge cache

However, my problem persists. What else can I try, or what else might be my problem?

Thanks, Kurt

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This is an oldish question, but for posterity, from what I can tell the above methods should have cleared the local machine's cache.

A likley reason you were still seeing NXDOMAIN is that your caching recursive resolver (i.e. "DNS server") was caching the NXDOMAIN response while other servers you were trying were using different caching resolvers that didn't have that negative result cached when you tried them and thus got and cached a valid record when you went to try them. A similar thing just happened to me. :-)

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