This is from the SANS Handler's
diary at http://isc.sans.org
ARIN in-addr.arpa
A post on the NANOG list indicates that the American Registry for Internet Numbers (ARIN, www.arin.net) is not providing reverse-lookup forwarding for any networks in the range 206.46.0.0 - 255.255.0.0. A quick "whois -h whois.arin.net 206.46.0.0" indicates this is a correct assessment at the time of this writing.
This issue is problematic for organizations who are blocking SMTP traffic from hosts that do not have matching forward and reverse DNS entries, since it is not currently possible to resolve these addresses from the authoritative source. This may result in the lack of mail delivery from host originating in this address range. This appears to be primarily affecting Verizon customers, who delegate addresses in this range to customers. No word from ARIN on the reason for the outage at this time.
http://www.merit.edu/mail.archives/nanog/msg04861.html
A post on the NANOG list indicates that the American Registry for Internet Numbers (ARIN, www.arin.net) is not providing reverse-lookup forwarding for any networks in the range 206.46.0.0 - 255.255.0.0. A quick "whois -h whois.arin.net 206.46.0.0" indicates this is a correct assessment at the time of this writing.
This issue is problematic for organizations who are blocking SMTP traffic from hosts that do not have matching forward and reverse DNS entries, since it is not currently possible to resolve these addresses from the authoritative source. This may result in the lack of mail delivery from host originating in this address range. This appears to be primarily affecting Verizon customers, who delegate addresses in this range to customers. No word from ARIN on the reason for the outage at this time.
http://www.merit.edu/mail.archives/nanog/msg04861.html
