Janu
ary 201
9
Legrand PDU User Guide 519
Role of a DNS Server
As Internet communications are carried out on the basis of IP addresses, appropriate DNS server settings
are required for mapping domain names (host names) to corresponding IP addresses, or the Legrand PDU
may fail to connect to the given host.
Therefore, DNS server settings are important for external authentication. With appropriate DNS settings, the
Legrand PDU can resolve the external authentication server's name to an IP address for establishing a
connection. If the
SSL/TLS encryption
is enabled, the DNS server settings become critical since only fully
qualified domain name can be used for specifying the LDAP server.
For information on external authentication, see
Setting Up External Authentication
(on page 188).
Cascading Troubleshooting
Any accessibility problem occurred on one of the devices in the cascading chain may result in failure to
access all downstream slave devices that are connected to it.
Possible Root Causes
The following lists the network accessibility issues and possible root causes.
You can always troubleshoot the software settings by connecting the Legrand PDU to a computer if network
access to that Legrand PDU fails. See
Connecting the Legrand PDU to a Computer
(on page 31).
Symptom
Probable cause
Failure to access the master
device
Anything below is lost or loose on the master device:
Network
connection
Power
supply
Anything below is disabled on the master device:
The Ethernet or wireless interface
IPv4 or IPv6 settings
In the Port Forwarding mode, related settings are
incorrectly configured on the master device.
The master device's role is incorrectly set to 'Slave'.
The interface where the network is connected is
incorrectly set as the downstream interface.
For the wireless networking, one of the following issues
occurs:
The USB wireless LAN adapter attached to the
master device is not the Raritan USB WIFI LAN
adapter. See
USB Wireless LAN Adapters
(on page
The wireless LAN configuration is not supported. See
Supported Wireless LAN Configuration
(on page
The installed CA certificate chain contains any
certificate that has expired or is not valid yet.