|Pivotal Greenplum (GPDB)||4.3.x|
Sometimes the customer may report being unable to ping certain hostnames but pinging the IP address works. Then it is an issue to resolve the hostname.
Here are a couple of items we can check to find the root cause of each hostname resolving issue:
Follow the steps to resolve this issue:
- Check the content of /etc/nsswitch.conf file, as this conf file will tell Linux which name-resolving method to use.
- Check /etc/hosts file. This file will help Linux directly resolve hostnames if this method is listed in the nsswitch.conf file.
- Check /etc/resolv.conf file. This file will tell if this host set up any DNS service yet.
- Check dnsmasq and nscd service. These two services can be used for the DNS cache. Sometimes the customer may ask why the hostname resolving is still working while /etc/hosts has no entry and the DNS service has stopped. The reason is that DNS cache service is still running.
Here are a few useful resources to know more about those Linux services: