Can you do the following in the Terminal and see if that works? "ping -c5 8.8.8.8" and "ping -c5 8.8.4.4"? If those two don't ping, then you can't resolve the names.
Colins-iMac:~ colinwebb$ ping -c5 8.8.8.8
PING 8.8.8.8 (8.8.8.8): 56 data bytes
64 bytes from 8.8.8.8: icmp_seq=0 ttl=119 time=20.674 ms
64 bytes from 8.8.8.8: icmp_seq=1 ttl=119 time=21.090 ms
64 bytes from 8.8.8.8: icmp_seq=2 ttl=119 time=18.294 ms
64 bytes from 8.8.8.8: icmp_seq=3 ttl=119 time=19.449 ms
64 bytes from 8.8.8.8: icmp_seq=4 ttl=119 time=16.903 ms
--- 8.8.8.8 ping statistics ---
5 packets transmitted, 5 packets received, 0.0% packet loss
round-trip min/avg/max/stddev = 16.903/19.282/21.090/1.541 ms
Colins-iMac:~ colinwebb$ ping -c5 8.8.4.4
PING 8.8.4.4 (8.8.4.4): 56 data bytes
64 bytes from 8.8.4.4: icmp_seq=0 ttl=121 time=20.213 ms
64 bytes from 8.8.4.4: icmp_seq=1 ttl=121 time=27.618 ms
64 bytes from 8.8.4.4: icmp_seq=2 ttl=121 time=20.082 ms
64 bytes from 8.8.4.4: icmp_seq=3 ttl=121 time=23.924 ms
64 bytes from 8.8.4.4: icmp_seq=4 ttl=121 time=17.351 ms
--- 8.8.4.4 ping statistics ---
5 packets transmitted, 5 packets received, 0.0% packet loss
round-trip min/avg/max/stddev = 17.351/21.838/27.618/3.567 ms
Colins-iMac:~ colinwebb$