You could try opening Terminal and running this command (to test):
ping google.com
then try
ping {one of the problem sites)
Here is what I get when I ping Google:
64 bytes from 74.125.21.102: icmp_seq=0 ttl=42 time=22.673 ms
64 bytes from 74.125.21.102: icmp_seq=1 ttl=42 time=24.882 ms
64 bytes from 74.125.21.102: icmp_seq=2 ttl=42 time=23.279 ms
64 bytes from 74.125.21.102: icmp_seq=3 ttl=42 time=24.849 ms
64 bytes from 74.125.21.102: icmp_seq=4 ttl=42 time=23.755 ms
64 bytes from 74.125.21.102: icmp_seq=5 ttl=42 time=22.011 ms
05-09-2015 02:48 PM