Recently I’d been having some bizarre network problems, the most consistent of which was that I couldn’t connect to the iTunes Store. After a short round of testing, I was quickly able to determine that the problem was DNS servers I was using.
Yes, I’m one of those people who uses those 4.2.2.x DNS servers, for probably 10 years they’ve worked perfectly.
While DNS servers can be set in the Mac’s System Preferences, that requires a lot of clicking and it’s faster to just use the networksetup command line tool. Since we’ll also be flushing the Directory Services cache with dscacheutil, switching servers can be condensed to one line making testing faster. Here’s an example of the command I’m using:
sudo networksetup -setdnsservers "AirPort" 126.96.36.199 && \
I repeated the above for each of the six known 4.2.2.x DNS servers. After individually setting each DNS server, I switched over to iTunes and attempted to access a different section of the iTunes Store.
188.8.131.52, 184.108.40.206, 220.127.116.11, 18.104.22.168, 22.214.171.124 and 126.96.36.199 all failed to connect to iTunes. Each of the servers appeared to be online and responded to pings with an average response time of about 12 ms.
When I switched to any of the top three recommended DNS servers on DNSServerList.org, I was able to connect to the iTunes Store instantly.
There have been a few tweets with similar problems, but I couldn’t find anything related to upgrades or other problems with the 4.2.2.x servers. I haven’t yet been able to test this on other connections but will post an addendum once I have.