Quoting Andrew McGlashan (andrew.mcglashan@affinityvision.com.au):
On 27/07/2012 8:46 AM, Craig Sanders wrote:
if you're comfortable with configuring and administering DNS and mail yourself you can probably find a virtual server with a static IP (essential for both NS and MX records) for not much more.
These days it is also essential that mail servers have a suitable reverse DNS (rDNS) entry as well.
It remains pragmatically useful for SMTP deliverability to have the MTA host's rDNS resolve to something valid. However, a few moments' thought will suggest why having rDNS exactly match forward lookup may be desirable but cannot ever become overwhelmingly important: because an IP can reverse to only one of potentially a myriad of forward A records. $ dig -t a linuxmafia.com. +short 198.144.195.186 $ dig -x 198.144.195.186 +short linuxmafia.COM. $ So far, so good, nei? However: $ dig -t a uncle-enzo.linuxmafia.com. +short 198.144.195.186 $ dig -t a enzo.linuxmafia.com. +short 198.144.195.186 $ dig -t a mail.linuxmafia.com. +short 198.144.195.186 $ dig -t a www.linuxmafia.com. +short 198.144.195.186 $ dig -t a ftp.linuxmafia.com. +short 198.144.195.186 $ dig -t a ns.linuxmafia.com. +short 198.144.195.186 $ dig -t a ns3.svlug.org. +short 198.144.195.186 $ dig -t a substancez.com. +short 198.144.195.186 $ dig -t a www.substancez.com. +short 198.144.195.186 $ dig -t a mail.substancez.com. +short 198.144.195.186 $ dig -t a ftp.substancez.com. +short 198.144.195.186 $ dig -t a substancez.net. +short 198.144.195.186 $ dig -t a www.substancez.net. +short 198.144.195.186 $ dig -t a mail.substancez.net. +short 198.144.195.186 $ dig -t a ftp.substancez.net. +short 198.144.195.186 $ dig -t a substancez.org. +short 198.144.195.186 $ dig -t a www.substancez.org. +short 198.144.195.186 $ dig -t a mail.substancez.org. +short 198.144.195.186 $ dig -t a ftp.substancez.org. +short 198.144.195.186 $ dig -t a ns3.svlug.net. +short 198.144.195.186 $ dig -t a unixmercenary.net. +short 198.144.195.186 $ dig -t a ns1.unixmercenary.net. +short 198.144.195.186 $ dig -t a www.unixmercenary.net. +short 198.144.195.186 $ dig -t a ns1.unixmercenary.net. +short 198.144.195.186 $ dig -t a ftp.unixmercenary.net. +short 198.144.195.186 As they said in the movie, there can be only one. -- Cheers, "Overheard a hipster say 'Quinoa is kind of 2011', Rick Moen so I lit his beard on fire." -- Kelly Oxford rick@linuxmafia.com McQ! (4x80)