Try to Flush/Clear DNS cache on your imac
<span id="INSERTION_MARKER">To clear dns cache in osx yosemite you need to run a command in terminal
dscacheutil -flushcache
HI
I recently switch my ISP and everything is OK excepts on my imac. Internet is working on windows laptop and fathers macbook pro, but my imac dont open almost any webpages.
its new imac 6month old with newes osx yosemite.
Please help

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