[ntp:questions] What happens if ntp server unavailable at start up?

Unruh unruh-spam at physics.ubc.ca
Fri Sep 12 22:43:12 UTC 2008

"Richard B. Gilbert" <rgilbert88 at comcast.net> writes:

>Evandro Menezes wrote:
>> On Sep 12, 8:31 am, Unruh <unruh-s... at physics.ubc.ca> wrote:
>>> Sounds great. So, let me say I have pool.ntp.org as a server. when my
>>> system comes up (a desktop) the network interface is there, but the dns
>>> server is still dead, and the gateway is still dead. Ie, no address for
>>> pool can be gotten from dns. Does the system keep trying or does it give up
>>> on that server?
>> Similarly, if a connection is dropped, will NTP query the DNS server
>> about the IP of a specified server again or will it binds to an IP
>> address and never give it up?

It does not query the dns server each time it sends out a packet. It
By connection I think he means tat association of name-IP and sending out
and receiving back packets. 

So by "connection dropped" I believe he means "send out a query packet and
receive no reply".

>There is NO "connection"!!  UDP, which is what NTP uses is a 
>connectionless protocol.  If a client receives no response to a query, 
>it is supposed to wait and try again, double the wait time and try 
>again, etc.  I believe that a conforming implementation is supposed keep 
>doubling the retry time until it reaches 1024 seconds.

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