ICMP is not guaranteed way to test connection over internet - many routers have ICMP limit, which causes the packet to be dropped
Check with mtr and there will be no losses on the last hop
Good point. Sorry about making an unfair assumption. Regardless, I'd still like to check the reliability of my connection to stratum.mining.cz. I tried running mtr stratum.bitcoin.cz a couple of times, and it seems to resolve to different addresses each time. Looks to me like some load balancing of some sort is going on, but it seems odd to me that it wouldn't just resolve to the closest geographical server to me every time. Sometimes it's smeu01.bitcoin.cz, sometimes it's 192.198.107.178, and sometimes it's 54.225.68.97 (ec2-54-225-68-97.compute-1.amazonaws.com).
Do you think manually specifying 54.225.68.97:3333 in my miner would be a good idea? 54.225.68.97 seems to have the lowest latency for me.