Re: Nameserver calls - libesmtp problem?

[Brian Stafford <brian stafford uklinux net>]

On Thu, 21 June 08:02 Albrecht Dreß wrote:

| Hmpf, thanks for the tip... now the nameserver call is gone. Looks as
| if I did
| not read the docs carefully enough and/or did not understand
| libesmtp's role

LibESMTP's role is to use SMTP to transfer submitted mail to an MTA.
Using the SMTP protocol directly eliminates the absolute requirement
for the submitting host to be running an MTA.

| Anyway, just curious: why *does* libesmtp call the nameserver?

It must resolve a domainname to one or more IP addresses.
This is the purpose of the domain name system.

| Transferring
| mails to a MTA would need a lookup of its address once (or never, if
| it is
| localhost), and then we can rest in peace. Or is this a too simplified
| view?

That is a simplified view.  When an application must resolve domain
names, they should always query a name server.  This is reccommeneded
practice for internet applications.  Applications should certainly
not cache results for themselves.  If a host is not permanently
connected to the internet, the use of a caching name server should
be considered.  Can't help so much here, DNS is not my thing.

| Thanks again, Albrecht.

Brian