IronPort AsyncOs 9.6.0-042 : DNS query network error '[Errno 55] No buffer space available'

[MessagingAdministration Paris]

Hello

Since we upgrade in AsyncOs  9.6.0-042, we are getting the following errors continuously :

Warning: DNS query network error '[Errno 55] No buffer space available' to '184.94.241.19' looking up '1-03aa8ec5db99b6d05dcd0efbeed2204d.28.29.199.91.v1x2s.rf-adfe2ko9.senderbase.org'

Warning: DNS query network error '[Errno 55] No buffer space available' to '184.85.248.67' looking up 'adns3.akam.net'

The ESA is a C380.

Does someone experience such issue ?

Regards

[Mathew Huynh]

Hello,

Please log into the CLI and use. CLI > etherconfig > media

and then check the MTU Ensure it's on full duplex and the MTU is set reasonably to ensure transmissions can be done without buffer issues seen.

Also check on the DNS side as well.

Regards,

Matthew

[MessagingAdministration Paris]

Hello,

Thank you for your reply.

DATA1 is configured on Full-Duplex, but not the management, could you think it can be the cause ?

Regards

Thierry

[Mathew Huynh]

Hello Thierry,

If it can be negotiated on full duplex (1000baseT / TX) then it would be suggested.

It could be the case if DNS (or many other packet transmissions) are using the MGMT IP for transfers.

Regards,

Matthew

[MessagingAdministration Paris]

Hello Mathew,

DNS is only configured on DATA1. The speed of the port is only 100 on DATA1 (1000 on one other of our CISCO ESA), could it be a cause ?

Regards

[Robert Sherwin]

Yes.  DNS can also show the same issue when there are pending connections/queries — buffer full, presents similar error notation.  If there are too many connections being made out over a slow network port, they'll stack & stale out, and create the error as you were seeing.  Running Data1 and Data2 on a 100 interface is not recommended - assureing that both the ESA and the switch they are connected to are set to AUTO or 1000 is preferable for communication.

-Robert