[ntp:questions] slow start

Danny Mayer mayer at ntp.isc.org
Tue May 29 09:03:09 UTC 2007


Richard B. Gilbert wrote:
> Jammer wrote:
>> Incredibly slow /etc/init.d/ntpd start
>> (it hangs on boot so I do it manually but it is slow).
> <snip>
>> Is it a hardware problem?
>> The computer clock seems to work fine.
>>
>> Should I be able to ping all the ntp servers in my /etc/ntp.conf?
>> I can't.
> 
> Normally, you should be able to ping NTP servers.
> 
> You should not, however, start your troubleshooting by pinging your NTP 
> servers.  Start by pinging something on your local network such as your 
> router or another computer.  Success tells you that your computer is 
> able to talk to your local network.
> 
> If you didn't ping your router, do it now.  If it doesn't respond, you 
> have some idea where to look for your problem.
> 
> Next, ping your ISP's gateway.  If that works, you've established that 
> you can connect to the internet.
> 
> Now try pinging your NTP servers.
> 

Before you do that ping the nameservers listed in the resolv.conf file.
They need to be available in order to resolve the names in your
ntpd.conf file.

> Try ntpdate -dU <server address>
> Do you get a response?  (This should not set your clock, it should just 
> tell you what ntpdate would have done if you had allowed it to.)
> 
> If you get no response, try:
> nslookup <fully qualified domain name of NTP server>
> 

Don't use nslookup, use dig. nslookup is really bad as a diagnostic tool.

Danny

> Does that return a numeric IP address in "dotted decimal" form?  It 
> should look like 123.231.135.7 (the numbers will be different; I just 
> pulled those out of my a**!).  If so, DNS is working.  If not, you 
> probably need to get professional help from your ISP's help desk.
> 
> You might also try issuing:
> 
> ntpq -p
> 
> That should list all your configured servers.  The "reach" field should
> show "377" for each server if ntpd has been running for at least 30 
> minutes.  If the reach field shows 0 you are unable to get a reply from 
> that server.  If they all say 0, you have some sort of a configuration 
> or network problem.  If you get some value greater than 0 but less than 
> 377 you are having only partial success reaching your servers.



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