UCMDB has two part discovery to decide which is the primary ip when using Host connection by shell
The part one ,the dicovery of interface and then get the ipaddress , and it uses ipaddress to query out hostname through DNS server.
The hostname output the DNS server is random. Different machine may have different out put.(Linux or windows and both of them have a lot of different versions). So it is decide by DNS server , not by UCMDB server.
The part two is the usage of the command to get hostname(only can get one hostname), UCMDB uses the part two host name to match part one hostname to decide which ip is primary ip.
QCIM1H126441 has an attachment which is a diagram that explains this and further explanation of the process provided by Ping from RnD