How to stop LLDP discovery of failed - Check name lookup


I have a lot event message “LLDP discovery of xxx failed - Check name lookup”

Can i keep autodiscovery enabled, find the new device but after find the device using LLDP/CDP (xdp) , then don’t check it against DNS/ name lookup.

This is our information

“LLDP discovery of cat03.access.psn.apjii.MMR-O failed - Check name lookup”

[email protected]:/opt/librenms$ ./discovery.php -h cat03.access.psn.apjii.MMR-O -d
LibreNMS Discovery
SQL[select migration from migrations order by id desc limit 1 [] 0.34ms]

SQL[select count(*) as aggregate from migrations limit 1 [] 0.24ms]

SQL[SELECT version() [] 0.33ms]

Version info:
Commit SHA: 4f7c7b3f2a7dfec3ccbe0be28c9616d93a56cf60
Commit Date: 1626216064
DB Schema: 2021_25_01_0127_create_isis_adjacencies_table (211)
PHP: 7.4.3
MySQL: 10.3.29-MariaDB-0ubuntu0.20.04.1
RRDTool: 1.7.2
Updating os_def.cache
SQL[SELECT * FROM devices WHERE disabled = 0 AND snmp_disable = 0 AND hostname LIKE ‘cat03.access.psn.apjii.MMR-O’ ORDER BY device_id DESC [] 0.51ms]

./discovery.php cat03.access.psn.apjii.MMR-O 2021-07-14 08:54:50 - 0 devices discovered in 0.311 secs
MySQL [1/0.00s]: Cell[1/0.00s] Row[-1/-0.00s] Rows[1/0.00s] Column[0/0.00s] Update[0/0.00s] Insert[0/0.00s] Delete[0/0.00s]
RRD [0/0.00s]:

[email protected]:/opt/librenms$ ./validate.php

Component Version
LibreNMS 21.6.0-46-g4f7c7b3f2
DB Schema 2021_25_01_0127_create_isis_adjacencies_table (211)
PHP 7.4.3
Python 3.8.10
MySQL 10.3.29-MariaDB-0ubuntu0.20.04.1
RRDTool 1.7.2


[OK] Composer Version: 2.1.3
[OK] Dependencies up-to-date.
[OK] Database connection successful
[OK] Database schema correct
[FAIL] We have found some files that are owned by a different user than ‘librenms’, this will stop you updating automatically and / or rrd files being updated causing graphs to fail.
sudo chown -R librenms:librenms /opt/librenms
sudo setfacl -d -m g::rwx /opt/librenms/rrd /opt/librenms/logs /opt/librenms/bootstrap/cache/ /opt/librenms/storage/
sudo chmod -R ug=rwX /opt/librenms/rrd /opt/librenms/logs /opt/librenms/bootstrap/cache/ /opt/librenms/storage/


You can have a look at the documentation which explains it :

Most importantly, the part to allow discovery by IP and not only by DNS.

You’ll still have a few errors because auto-discovery, by definition, will run again and again each night unless you disable it. So each night it will retry all xDP neighbours and probably fail again on the same ones.

1 Like

Hi PipoCanaja,

i think i work now.
i add on config.phjp

$config[‘discovery_by_ip’] = true;

thank’s for your help.

i changed
$config[‘discovery_by_ip’] = true;
$config[‘discovery_by_ip’] = false;

after changing should i restart the server?

the notification "LLDP discovery of xxxxx failed - Check name lookup"still show up filling the event dashboard.


There is nothing to restart. And the notifications will remain as long as you keep LLDP autodiscovery enabled and you have devices that cannot be discovered. This is completely normal.

Please let us know what you want to do.

This topic was automatically closed 7 days after the last reply. New replies are no longer allowed.