I've updated to Mountain Lion, and I'm having some DNS problems. I always PPTP/L2TP VPN connections on my macbook. Recently after a while of working with Mountain Lion, VPN stops sending and receiving data and I have to disconnect/connect again to make it work again. I'm not having the same problem with iPad, iPhone and PC.
and without the VPN, when I try pinging 18.104.22.168 , 22.214.171.124 and other DNSs and all I get is timeouts! But the ping works fine on my other devices. I also tried setting the DNS to Google and OpenDNS DNSs (126.96.36.199, 188.8.131.52, 184.108.40.206, ...) but it still didn't help. I also tried emptying DNS cache and other solutions. but nothing.
I'm guessing that these two problems are tied together. Any solutions?