On 2011/12/30 18:11, MT Julianto wrote:
> On 31 December 2011 03:01, jdow <[log in to unmask] <mailto:[log in to unmask]>>
> wrote:
>
>     On 2011/12/30 17:24, MT Julianto wrote:
>
>         On 30 December 2011 14:15, jdow <[log in to unmask]
>         <mailto:[log in to unmask]> <mailto:[log in to unmask]
>         <mailto:[log in to unmask]>>>
>             What happens if you ping the host before trying ssh?
>
>         Sometimes it failed as well.
>
>
>     As in the ssh login failed after the ping failed or did the ping find the
>     host and you still had an ssh failure.
>
>
> I mean the ping is failed sometimes, but ssh login afterward is succeeded.

Bingo - if the numeric address of the destination machine changes fairly
frequently for one reason or another or if its DNS entry has a short enough
TTL the DNS lookup might fail the first try and succeed on the second after
the DNS server has finally received the information from the authoritative
sources it uses. It's something I remember seeing happen long ago. I've not
seen it recently. But then my address has been staying remarkably constant
for a long time now compared to the times I am on the road trying to get
into my machine. (I use dnsalias to find myself. Back in the mid 90s I
used a perverted "ping" command to trigger my remote machine to respond
to me with its address. I'd figured out the range of addresses it might be
on and made a broad enough ping request with a specific payload to the ping.
Yea verily I have sinned - but the statute of limitations has run out.)

{^_^}