Changes

* SME has IP Address a.b.c.d

* SME has IP Address a.b.c.d

* SME has domain name mysmeserver.com

* SME has domain name mysmeserver.com

* Remote_User is configured to use Other_DNS for DNS lookups

* '''Remote_User''' is configured to use '''Other_DNS''' for DNS lookups

If Remote_User tries to browse to http://mysmeserver.com, his computer asks Other_DNS how to find 'mysmeserver.com'.  Other_DNS server then

If Remote_User tries to browse to http://mysmeserver.com, his computer asks '''Other_DNS''' how to find 'mysmeserver.com'.  '''Other_DNS''' server then

* asks the Root_DNS servers for the Registrar in charge of 'mysmeserver.com'

* asks the '''Root_DNS''' servers for the '''Registrar''' in charge of 'mysmeserver.com'

* asks the Registrar for the DNS_Server that will answer queries about 'mysmeserver.com'

* asks the '''Registrar''' for the '''DNS_Server''' that will answer queries about 'mysmeserver.com'

* asks the DNS_Server for the IP address of 'mysmeserver.com'

* asks the '''DNS_Server''' for the IP address of 'mysmeserver.com'

* saves the answer in its local cache for the amount of time specified by the administrator of the DNS record at DNS_Server.

* saves the answer in its local cache for the amount of time specified by the administrator of the DNS record at '''DNS_Server'''.

If, on the other hand, Remote_User asks for information about your IP address (a.b.c.d), his DNS server

If, on the other hand, '''Remote_User''' asks for information about your IP address (a.b.c.d), his DNS server

* asks the Root_DNS servers where d.c.b.a.in-addr.arpa is registered.

* asks the '''Root_DNS''' servers where d.c.b.a.in-addr.arpa is registered.

* asks the Registrar where to get more info about d.c.b.a.in-addr.arpa.  This is probably but not necessarily Your_ISPs_DNS.

* asks the '''Registrar''' where to get more info about d.c.b.a.in-addr.arpa.  This is probably but not necessarily '''Your_ISPs_DNS'''.

* asks the host indicated by the Registrar (probably Your_ISPs_DNS) what name belongs to 'd.c.b.a.in-addr.arpa'.  The return value is almost always a generic filler based on your IP address unless you contact your ISP and ask them to change the PTR data for your IP address.

* asks the host indicated by the '''Registrar''' (probably '''Your_ISPs_DNS''') what name belongs to 'd.c.b.a.in-addr.arpa'.  The return value is almost always a generic filler based on your IP address unless you contact your ISP and ask them to change the PTR data for your IP address.

Basically, PTR records are managed by the organization that controls the IP address (which makes sense, if you think about it).

Basically, PTR records are managed by the organization that controls the IP address (which makes sense, if you think about it).