On Monday 19 March 2007 11:52, Stuart D. Gathman wrote:
On Sun, 18 Mar 2007, Frank Ellermann wrote:
Stuart D. Gathman wrote:
I'm not convinced that a label with no dot is a FQDN.
I'll have to look up the definition.
You really think TLDs are no FQDNs ? The best explanation
I know (and for that reason also an informative reference
in RFC 4408) is http://tools.ietf.org/html/rfc3696#section-2
| Consequently, purported DNS names to be used in applications
| and to locate resources generally must contain at least one
| period (".") character. Those that do not are either invalid
| or require the application to supply additional information.
| Of course, this principle does not apply when the purpose of
| the application is to process or query TLD names themselves.
Since the purpose of SPF is *not* to process or query TLD names
themselves, I'd say I'm more convinced than ever that TLDs are no
FQDNs in the context of SPF. Thanks for quoting that.
Interesting. Elsewhere there is guidance that says not to assume you have a
complete/correct list of TLDs and that the only thing that should parse as
invalid for a TLD is all numeric (I'll dig out the reference if anyone
cares).
Since we now allow a trailing dot and the purpose of an SPF library is most
definitely not to process or query TLD names themselves, it seems to me that
the reasonable approach would be to use the dot test for FQDN (has a dot and
TLD is not all numeric). Thus:
museum - Not a TLD, SPF result is always none.
museum. - Is a TLD, lookup the TXT record.
This allows TLDs to do SPF if they so choose, but doesn't force us to treat
OEMCOMPUTER as a TLD and thus cause lots of unnecessary DNS lookups.
Scott K
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