check_ping necessary?

[Stanley Hopcroft]

Dear Sir,

I am writing to thank you for your letter and say,

On Thu, Jan 02, 2003 at 03:55:37PM -0600, Don Schultz wrote:
> This may be a really stupid question but I'm going for it anyways ;)
> 
> Is it necessary to define a "ping" service for hosts? 

No. However you must define at least _one_ service. Most choose to 
define ping as well as other services because in most cases you probably 
want to to be informed that a host is unreachable __before__ (owing to 
the way Nagios works) that it activates the host checking logic.

> If you do not,
> aren't they still pinged with the check-host-alive command or are they
> just assumed to be up by the nagios process? 

You should read the theory of operation.

In a nutshell, check-host-alive is only scheduled after a service check 
returns a HARD CRITICAL state.

You have two opions

1 Define services >= 1 + ping

  ==> notified if host becomes unreachable at service check time

2 Define services(excluding ping) >= 1

  ==> notified when host becomes unreachable only after a service check 
cycle reports a service failure.

> 
> If I'm thinking correctly, then the only way to get notification of a
> host being "down" is to include it in a ping service definition correct?
>

No. Hosts are always checked if a service fails. The service does not 
have to be a 'ping' service.
 
> Thanks!
>

Yours sincerely. 

-- 
------------------------------------------------------------------------
Stanley Hopcroft
------------------------------------------------------------------------

'...No man is an island, entire of itself; every man is a piece of the
continent, a part of the main. If a clod be washed away by the sea,
Europe is the less, as well as if a promontory were, as well as if a
manor of thy friend's or of thine own were. Any man's death diminishes
me, because I am involved in mankind; and therefore never send to know
for whom the bell tolls; it tolls for thee...'

from Meditation 17, J Donne.


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