North American Network Operators Group|
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Re: Identifying IP address types (fwd)
Public reply, because private are blocked. > http://www.ietf.org/internet-drafts/draft-stumpf-dns-mtamark-01.txt > uses rev-dns TXT RRs to let admins document which IP addresses are > supposed to act as MTA (as well as to document which addresses are > supposed not to send mail). The difference is an ISP may "permit" any customer to act as an MTA. The ISP does not want to decide about what to permit or deny. But the ISP may be willing to provide more information about an address so other people can decide if they want to behave differently depending on the type of connection. For example, an IRC operator may decide not to permit anyone using a dynamic address to connect, or a Web site may want to send smaller pages to users on low bandwidth connections. > In fact, you won't be able to reply to this email unless > [email protected] enters > > @origin 53.34.199.in-addr.arpa > _perm._stmp_srv.180 IN TXT "1" > > into the DNS for you. If an ISP permits every IP address to use any service, what does it accomplish? If an ISP didn't want to permit its users to access SMTP, the ISP would just block port 25 at the network layer.