Temporary failure in name resolution - fsockopen()

We recently para-virtualised a Xen / CentOS box which is running script
which uses fsockopen() to get a connection to an SMTP server.

Since the server changes it fails approx 50% of the time with:

"php_network_getaddresses: getaddrinfo failed: Temporary failure in name
resolution"

We've tried the solutions from Googling this error (such as restarting
Apache etc), but without success.

Why am I wasting your time with a Linux upgrade issue? Well,
gethostbyname() seems to resolve the IP every time. Manual lookups on
from the server seem to work with no problems.

Any help greatly appreciated. Should I perhaps be pointing this out on
the 'internals' list?

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Re: Temporary failure in name resolution - fsockopen()

On 03/25/2010 03:51 PM, David Lidstone wrote:
> We recently para-virtualised a Xen / CentOS box which is running script
> which uses fsockopen() to get a connection to an SMTP server.
>
> Since the server changes it fails approx 50% of the time with:
>
> "php_network_getaddresses: getaddrinfo failed: Temporary failure in name
> resolution"
>
> We've tried the solutions from Googling this error (such as restarting
> Apache etc), but without success.
>
> Why am I wasting your time with a Linux upgrade issue? Well,
> gethostbyname() seems to resolve the IP every time. Manual lookups on
> from the server seem to work with no problems.
>
> Any help greatly appreciated. Should I perhaps be pointing this out on
> the 'internals' list?
>

I feel its something do with your DNS settings and/or the server.

If that's not the problem then just as a temp solution add your SMTP
server's address provided it has a static IP (99.9% it has) to your
/etc/hosts file.

It should not give trouble then.

--
Nilesh Govindarajan
Site & Server Administrator
www.itech7.com

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Re: Temporary failure in name resolution - fsockopen()

Nilesh Govindarajan wrote:
> On 03/25/2010 03:51 PM, David Lidstone wrote:
>> We recently para-virtualised a Xen / CentOS box which is running script
>> which uses fsockopen() to get a connection to an SMTP server.
>>
>> Since the server changes it fails approx 50% of the time with:
>>
>> "php_network_getaddresses: getaddrinfo failed: Temporary failure in name
>> resolution"
>>
>> We've tried the solutions from Googling this error (such as restarting
>> Apache etc), but without success.
>>
>> Why am I wasting your time with a Linux upgrade issue? Well,
>> gethostbyname() seems to resolve the IP every time. Manual lookups on
>> from the server seem to work with no problems.
>>
>> Any help greatly appreciated. Should I perhaps be pointing this out on
>> the 'internals' list?
>>
>
> I feel its something do with your DNS settings and/or the server.
>
> If that's not the problem then just as a temp solution add your SMTP
> server's address provided it has a static IP (99.9% it has) to your
> /etc/hosts file.
>
> It should not give trouble then.
>

Thanks for your suggestion Nilesh, but the hosts file would seem to just
defeat the object of being able to look up DNS addresses.

It is possible to by-pass the issue by using gethostbyname() and just
passing in the IP, but this is not really a solution (e.g. we regularly
use a PEAR package which is now effected). The real questions in my mind
are:

"If there is a reliable call to resolve IPs, then what is fsockopen()
doing which is different? Given the recurrence of this error over the
last 8 - 9 years, can it be changed to improve reliability, or is this
just a one-off with our server?"

I do agree that it is almost certainly an issue with the server or a
library being used (me != serverexpert). But what and why and can PHP
work around this better internally? Thanks again.

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Re: Temporary failure in name resolution - fsockopen()

On 03/25/2010 07:01 PM, David Lidstone wrote:
> Nilesh Govindarajan wrote:
>> On 03/25/2010 03:51 PM, David Lidstone wrote:
>>> We recently para-virtualised a Xen / CentOS box which is running script
>>> which uses fsockopen() to get a connection to an SMTP server.
>>>
>>> Since the server changes it fails approx 50% of the time with:
>>>
>>> "php_network_getaddresses: getaddrinfo failed: Temporary failure in name
>>> resolution"
>>>
>>> We've tried the solutions from Googling this error (such as restarting
>>> Apache etc), but without success.
>>>
>>> Why am I wasting your time with a Linux upgrade issue? Well,
>>> gethostbyname() seems to resolve the IP every time. Manual lookups on
>>> from the server seem to work with no problems.
>>>
>>> Any help greatly appreciated. Should I perhaps be pointing this out on
>>> the 'internals' list?
>>>
>>
>> I feel its something do with your DNS settings and/or the server.
>>
>> If that's not the problem then just as a temp solution add your SMTP
>> server's address provided it has a static IP (99.9% it has) to your
>> /etc/hosts file.
>>
>> It should not give trouble then.
>>
>
> Thanks for your suggestion Nilesh, but the hosts file would seem to just
> defeat the object of being able to look up DNS addresses.
>
> It is possible to by-pass the issue by using gethostbyname() and just
> passing in the IP, but this is not really a solution (e.g. we regularly
> use a PEAR package which is now effected). The real questions in my mind
> are:
>
> "If there is a reliable call to resolve IPs, then what is fsockopen()
> doing which is different? Given the recurrence of this error over the
> last 8 - 9 years, can it be changed to improve reliability, or is this
> just a one-off with our server?"
>
> I do agree that it is almost certainly an issue with the server or a
> library being used (me != serverexpert). But what and why and can PHP
> work around this better internally? Thanks again.

One point to be noted here is that you're using CentOS. CentOS has very
old packages and libraries. So that could be a reason. I don't deny that
CentOS is a free alternative to most used RHEL, but still old is old,
new is new. Old is gold doesn't apply in the IT world.

Try upgrading to a new version or use Arch Linux / Gentoo to get the
latest software and libraries.

--
Nilesh Govindarajan
Site & Server Administrator
www.itech7.com

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Re: Temporary failure in name resolution - fsockopen()

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Content-Type: text/plain; charset=UTF-8

For faster dns lookup you can install dnsmasq package and make the local
server cache.
May be that'll solve your problem and the server will be faster.


Shiplu Mokaddim
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