Jay Ashworth <jra@baylink.com> writes:
----- Original Message -----
From: "John Levine" <johnl@iecc.com>
The public suffix list contains points in the DNS where (roughly speaking) names below that point are under different management from each other and from that name. It's here: http://publicsuffix.org/
The idea is that abc.foo.com and xyz.foo.com have the same management, but abc.co.uk and xyz.co.uk do not.
You don't have to tell me that it's a gross crock, but it seems to be a useful one. What do people use it for? Here's what I know of:
* Web browsers use it to manage cookies to keep a site from putting cookies that will affect other sites, e.g. abc.foo.co.uk can set a cookie for foo.co.uk but not for co.uk.
* DMARC (www.dmarc.org) uses it to find a policy record in the DNS that describes a subtree, e.g., if you get mail that purports to be from eBay@reply1.ebay.com it checks the policy at ebay.com.
What other current applications are there?
Seems to me that it's a crock because *it should be in the DNS*.
It is already, isn't it? The NS and SOA records will tell you all there is to know about zone splits and cross zone relations.
I should be able to retrieve the AS (administrative split) record for .co.uk, and there should be one that says, "yup, there's an administrative split below me; nothing under there is mine unless you also get an exception record for a subdomain".
Use the SOA record. If it is identical for two zones, then the adminstrative authority for those zones is the same. For example, "microsoft.co.uk" and "microsoft.com" can be considered under the same administration: bjorn@nemi:~$ dig +short soa microsoft.co.uk ns1.msft.net. msnhst.microsoft.com. 2013032601 1800 900 2419200 3600 bjorn@nemi:~$ dig +short soa microsoft.com ns1.msft.net. msnhst.microsoft.com. 2013041803 300 600 2419200 3600 While "apple.co.uk" and "apple.com" may be, depending on how strict you are going to be when comparing: bjorn@nemi:~$ dig +short soa apple.co.uk nserver.euro.apple.com. hostmaster.apple.com. 10 1800 900 2592000 1800 bjorn@nemi:~$ dig +short soa apple.com gridmaster-ib.apple.com. hostmaster.apple.com. 2010086586 1800 900 2016000 86500 etc. Bjørn