The total bandwidth used according to my calc is 1414 B. So their number of 138 KB is actually 1.38 KB (which is 1380 B, and that's closer to my number. I rounded up if you look at my numbers)
So their number of 715 MB is actually right. Just an error with 138 KB -> 1.38 KB
Whoops. Made it to the front page of HN with so many mistakes.
EDIT:
Since there seems to be interest in this let's do the test:
5 DNS requests + 1 NTP update according to the article (seems weird that it would resolve all the the NTP servers, but lets roll with it)
DNS: dig <domain> (mean for request is 43.8 B and reply is 84.6 B)
NTP: busybox_NTPD -n -q -p time.nist.gov
---------------------
Egress:
Single DNS request : 20 (IP) + 8 (UDP) + 44 (DNS) = 72 B
NTP request (2 packets): 20 (IP) + 8 (UDP) + 48 (NTP client) = 76 B
Total egress: 72x6 + 76x2 = 584 B
----------------------
Ingress:
Single DNS reply: 20 (IP) + 8 (UDP) + 85 (DNS) = 113 B
NTP reply (2 packets): 20 (IP) + 8 (UDP) + 48 (NTP server) = 76 B
Total Ingress: 113x6 + 76x2 = 830 B
----------------------
The total bandwidth used according to my calc is 1414 B. So their number of 138 KB is actually 1.38 KB (which is 1380 B, and that's closer to my number. I rounded up if you look at my numbers)
So their number of 715 MB is actually right. Just an error with 138 KB -> 1.38 KB