On Thu, May 2, 2013 at 2:12 PM, Patrick W. Gilmore <patrick@ianai.net>wrote:
On May 02, 2013, at 12:12 , Joe Abley <jabley@hopcount.ca> wrote:
On 2013-05-02, at 12:10, Joe Abley <jabley@hopcount.ca> wrote:
On 2013-05-02, at 11:59, Charles Gucker <cgucker@onesc.net> wrote:
That's not entirely true. You can easily do lookup for whoami.akamai.net and it will return the unicast address for the node in question (provided the local resolver is able to do the resolution). This is a frequent lookup that I do when I don't know what actual anycast node I'm using.
Using 8.8.8.8 to tell me about whoami.akamai.net tells me what Akamai authoritative server Google last used to answer that query.
Oh, now that I poke at it, it seems like whoami.akamai.net is telling me about the address of the resolver I used, rather than the address of the akamai node I hit.
Never mind, I understand now :-)
For clarity: Looking up the hostname "whoami.akamai.net" will return the IP address in the source field of the packet (DNS query) which reached the authoritative name server for Akamai.net.
We use this to look for forwarding or proxying, which is frequently unknown / invisible to the end user.
It has the side-effect that querying against an anycast server (e.g. 208.67.222.222 or 8.8.8.8) will show the unicast address of the anycast node which forwarded to our servers.
'the unicast address of the exit for upstream/cache-fill lookups' .. since the topology behind the anycast node isn't necessarily: internet -> anycast-ip -|host|- unicast-ip ... there could be some networking between |host| and the outside world, or other things going on. anyway... nit-picking-aside, cool that there's a way to figure this sort of thing out :) google has a similar method, which I can't find today :( <darn webcrawler!!!>