Why are some devices added with IP-address instead of host name?

Devices with unresolved hostname are added into OpManager with the help of IP address.

If the device is added with its IP address instead of hostname, check the following:

• Forward NSLOOKUP with the device name should return the IP address and DNS Name of the device.
  
• Reverse NSLOOKUP with the IP address should return the IP address and DNS Name of the device.
  

Devices are added using its hostname only if both the forward and reverse NSLOOKUP return corresponding parameters. Make sure that the hostname and IP address is mapped properly in the DNS server and ensure that the device is reachable from OpManager server.