[dns-operations] bind + client-subnet

Jared Mauch jared at puck.nether.net
Tue Aug 13 10:53:11 UTC 2013

On Aug 13, 2013, at 6:47 AM, Ken Peng <pyh2 at att.net> wrote:

> On 2013-8-13 18:30, Jared Mauch wrote:
>> I'm not sure how accurate this really is, but:
>> http://www.cdnplanet.com/blog/which-cdns-support-edns-client-subnet/
>> Basically, it helps pass the client IP upstream so the CDN can make a better guess to which cluster to direct you to, instead of the query-source IP of the recursive they are talking to.
> but how to implement that? since local DNS server always has caching.

The CDNs typically do this through chained CNAMES, with one of them having a low TTL. 

swcdn.apple.com.	3242	IN	CNAME	swcdn.apple.com.akadns.net.
swcdn.apple.com.akadns.net. 38	IN	CNAME	swcdn.apple.com.c.footprint.net.

- Jared

More information about the dns-operations mailing list