What is the difference between "No address associated with name" and "Unknown host"

[Abdullah Al-Marrie]

On 12/4/06, a at zeos.net <a at zeos.net> wrote:
> What is the difference between "No address associated with name"
> and "Unknown host":
>
> $ ping accounts.eirtrade.ie
> ping: cannot resolve accounts.eirtrade.ie: No address associated with name
>
> and
>
> $ ping accounts.eirtrade.i
> ping: cannot resolve accounts.eirtrade.i: Unknown host
>
> The source of my interest is the next.
>
> My sendmail receives mail from senders with domains like the first,
> but rejects mail from the last:
>
> ------------------------------------------------------------------------
> $ telnet localhost 25
> Trying ::1...
> telnet: connect to address ::1: Connection refused
> Trying 127.0.0.1...
> Connected to localhost.
> Escape character is '^]'.
> 220 host.my.domain ESMTP Sendmail 8.13.7/8.13.6; Mon, 4 Dec 2006 21:38:50 +0200
> (EET)
> HELO localhost
> 250 host.my.domain Hello localhost [127.0.0.1], pleased to meet you
> MAIL From: asdf at accounts.eirtrade.ie
> 250 2.1.0 asdf at accounts.eirtrade.ie... Sender ok
> RSET
> 250 2.0.0 Reset state
> MAIL From: asdf at accounts.eirtrade.i
> 553 5.1.8 asdf at accounts.eirtrade.i... Domain of sender address
> asdf at accounts.eirtrade.i does not exist
> QUIT
> 221 2.0.0 host.my.domain closing connection
> Connection closed by foreign host.
> ------------------------------------------------------------------------
>
> Elisej Babenko

I get the same problem with my laptop which uses DHCP in FreeBSD
6.2-RC1 and earlier was using 6.1-S, this happens to me regurarely
even I just opened an address in FF, then again trying to open same
host via FF.

Is there away to cache dns locally in my laptop?

Thank you,

-Abdullah