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Lukas Zapletal, 09/22/2016 03:31 AM
Elaborated the article


ERF50-9294 Failed to save: failed to detect boot server

ERF50-9294 [Foreman::WrappedException]: Unable to find IP address for 'foreman.home.lan' ([Resolv::ResolvError]: DNS result has no information for foreman.home.lan)

This happens when hostname set in the tftp_servername option (TFTP Smart Proxy by default) has no valid DNS record via DNS servers set in SOA/NS record of the domain. Foreman resolves the hostname set in tftp_servername to an IP address in order to ensure clients boots without any DNS requests.

By default, Foreman explicitly contacts DNS servers configured in the SOA therefore it ignores system-wide DNS setting (resolv.conf, /etc/hosts etc). This can lead to issues and this may be unexpected behavior for some administrators.

Luckily, there is a global setting "Query local nameservers" available to change that behavior. Foreman will query the locally configured resolver instead of the SOA/NS authorities when the setting is set.

As an alternative, set the tftp_servername configuration value to IP address instead DNS name, therefore Foreman won't need to resolve the hostname.

The relevant setting can be found on the Smart Proxy (make sure to restart foreman-proxy process when changing):

[root@myproxy ~]# cat /etc/foreman-proxy/settings.d/tftp.yml 
---
:enabled: true
:tftproot: /var/lib/tftpboot/
:tftp_servername: 192.168.99.1

Foreman installer can set this automatically via --foreman-proxy-tftp-servername option.