mouss:
> Noel Jones a ?crit :
> > Thomas wrote:
> >> Thomas Ackermann wrote:
> >>> So, does anybody know what technically is the difference between the
> >>> use with and without the signs?
> >>> I mean, what network things may happen or not happen?
> >>
> >> Nobody knows the technical differences?
> >>
> >> :-(
> >
> > ... more likely nobody cares, because postfix behavior is documented.
> >
> > When the relayhost is a hostname enclosed by "[ ]" brackets, postfix
> > asks for an A record and does not ask for an MX record.
> >
> > If relayhost is an IP address enclosed by brackets, postfix uses that IP
> > with no additional lookups.
> >
> > If realyhost is a hostname with no brackets, postfix will request an MX
> > record, if no MX exists, postfix will then request an A record.
> >
> > If relayhost is an IP address with no brackets, postfix will request a
> > PTR lookup to find the hostname, then request an MX lookup on that
> > hostname. If no MX record exists, then an A record is requested for the
> > hostname. Either the MX lookup or the A lookup may return a result
> > different from the original bare IP; this is why you should always
> > enclose a literal IP address relayhost in brackets.
> >
>
> hmmm. smtp(8) doesn't list "naked IP" as a valid destination format. only
Not listed, but allowed for backwards compatibility. When the host
is an IP address, Postfix calls the getaddrinfo() library routine
with a hint of AI_NUMERICHOST.
If the AI_NUMERICHOST bit is set in the ai_flags member of the hints
structure, then a non-NULL nodename string must be a numeric host address
string. Otherwise an error of EAI_NONAME is returned. This flag pre-
vents any type of name resolution service (e.g., the DNS) from being
called.
Apparently some systems resolve the address to name anyway.
Wietse
