Postgresql responses are slow without internet I have a Postgres service in Centos 7 and it works normally.

Each time when the internet service (by an IPS) is down, the responses are slow, other times the DNS is reset by an electrical trouble, forcing to set 192.168.2.1, and the responses are slow too.

Trying to solve the trouble, I change the DNS (192.168.2.1 - this is my lan dns) to [8.8.8.8] (google's one) and the responses comes back to work normally.

Anyone can tell why this happens?
Have I configured something wrong in the installation?

Note: this happens in 15 database servers (one per store).
something is doing dns lookups on your connections, check your logging settings are not logging domain names, and ensure that pg_hba.conf contains no host names (only ip addresses)  

perhaps use wireshark or tshark to check for DNS traffic on the database server and see what the lookups are.