Should I use Google Public DNS?

26Jan10

I read from a lot of blogs regarding Google’s Public DNS service and most of the blogs said it is very fast, but, before jumping to the bandwagon, I would like to know how much I can trust these information? So I just follow what the Redmonk compared OpenDNS and Google’s Public DNS by comparing DNS servers of my local provider to Google’s.

1) Starts with Ping:

$ ping 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=240 time=146.142 ms
64 bytes from 8.8.8.8: icmp_seq=1 ttl=240 time=91.800 ms
64 bytes from 8.8.8.8: icmp_seq=2 ttl=240 time=91.480 ms
^C
— 8.8.8.8 ping statistics —
4 packets transmitted, 3 packets received, 25.0% packet loss
round-trip min/avg/max/stddev = 91.480/109.807/146.142/25.693 ms

$ ping y.y.y.y (my local provider)
PING 203.144.255.71 (203.144.255.71): 56 data bytes
64 bytes from 203.144.255.71: icmp_seq=0 ttl=244 time=13.228 ms
64 bytes from 203.144.255.71: icmp_seq=1 ttl=244 time=13.280 ms
64 bytes from 203.144.255.71: icmp_seq=2 ttl=244 time=13.400 ms
^C

This is 6 times difference. Well local provider is much closer to me so ping time should definitely be better. What about query time?

2) Doing a query:

$ dig @8.8.8.8 also-uncached-for-sure.[redacted].com

; <<>> DiG 9.6.0-APPLE-P2 <<>> @8.8.8.8 also-uncached-for-sure.[redacted].com
; (1 server found)
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NXDOMAIN, id: 14489
;; flags: qr rd ra; QUERY: 1, ANSWER: 0, AUTHORITY: 1, ADDITIONAL: 0

;; QUESTION SECTION:
;also-uncached-for-sure.[redacted].com. IN A

;; AUTHORITY SECTION:
com. 900 IN SOA a.gtld-servers.net. nstld.verisign-grs.com. 1264468967 1800 900 604800 86400

;; Query time: 375 msec
;; SERVER: 8.8.8.8#53(8.8.8.8)
;; WHEN: Tue Jan 26 08:23:06 2010
;; MSG SIZE rcvd: 128

$dig @203.144.255.71 uncached-for-sure.[redacted].com

; <<>> DiG 9.6.0-APPLE-P2 <<>> @y.y.y.y uncached-for-sure.[redacted].com
; (1 server found)
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: REFUSED, id: 778
;; flags: qr rd; QUERY: 1, ANSWER: 0, AUTHORITY: 0, ADDITIONAL: 0
;; WARNING: recursion requested but not available

;; QUESTION SECTION:
;uncached-for-sure.[redacted].com. IN A

;; Query time: 16 msec
;; SERVER: y.y.y.y#53(y.y.y.y)
;; WHEN: Tue Jan 26 08:23:34 2010
;; MSG SIZE rcvd: 50

16 msec vs 375 msec. This yet is too different!

So, I rather stick to using my local provider’s DNS as the primary DNS, Google’s DNS can only be my backup! Sorry Google.

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