(1) Steps to reproduce:

1. Configure Zabbix agent and Zabbix server at two different machines. This would be needed later to ensure that zbx_gethost_by_ip() function cannot resolve DNS by IP. In my case Zabbix server is located at machine 192.168.56.201 and Zabbix agent at machine 192.168.56.203.
2. Create a DNS address that resolves to Zabbix agent IP address. In my case it is 203.uggla.id.lv which resolves to IP 192.168.56.203.
3. zabbix_agentd.conf file should have these options defined.

   Server=192.168.56.201
   ServerActive=192.168.56.201:10051
   Hostname=Test autoreg
   HostMetadata=Training
   HostInterface=203.uggla.id.lv
   

1. Configure an autoregistration action:
   1. Condition: Host metadata contains Training
   2. Operation: Link templates: Zabbix agent active
2. Optional step. Template Zabbix agent active has 4 items. Is it convenient to set update period to some small value like 5 seconds. Also remove "Unchanged with heartbeat" preprocessing steps from the 2 items where they are configured.
3. Start Zabbix server and Zabbix agent

Note: a host can also be alternatively created manually at this step without using active agent autoregistration.

(1) Result:
A host with name Test autoreg is autoregistered.
The host has an interface:

1. IP 192.168.56.203
2. DNS 203.uggla.id.lv
3. Connected to DNS

(1)Expected:
The same as observed.

(2) Steps to reproduce:

1. Remove this option from the Zabbix agent config

   # HostInterface=203.uggla.id.lv
   

1. Restart Zabbix agent.

(2) Result:
A host with name Test autoreg is autoregistered.
The host has an interface:

1. IP 192.168.56.203
2. DNS <empty field>
3. Connected to IP

(2)Expected:

The expected part should be elaborated.