When using a directory monitor input, specific source types can be selectively overridden using the props.conf file. According to the Splunk documentation1, “You can specify a source type for data based on its input and source. Specify source type for an input. You can assign the source type for data coming from a specific input, such as /var/log/. If you use Splunk Cloud Platform, use Splunk Web to define source types. If you use Splunk Enterprise, define source types in Splunk Web or by editing the inputs.conf configuration file.” However, this method is not very granular and assigns the same source type to all data from an input. To override the source type on a per-event basis, you need to use the props.conf file and the transforms.conf file2. The props.conf file contains settings that determine how the Splunk platform processes incoming data, such as how to segment events, extract fields, and assign source types2. The transforms.conf file contains settings that modify or filter event dataduring indexing or search time2. You can use these files to create rules that match specific patterns in the event data and assign different source types accordingly2. For example, you can create a rule that assigns a source type of apache_error to any event that contains the word “error” in the first line2.

The possible causes of the load balancing issue on the Universal Forwarder are A and C. The receiving port and the DNS record are both factors that affect the ability of the Universal Forwarder to distribute data across multiple receivers. If the receiving port is not properly set up to listen on the right port, or if the DNS record used is not set up with a valid list of IP addresses, the Universal Forwarder might fail to connect to some or all of the receivers, resulting in poor load balancing.

This is because the input type is UDP, which is an unreliable protocol that does not guarantee delivery, order, or integrity of the data packets. UDP does not have any mechanism to resend or acknowledge the data packets, so if Splunk is restarted, any data that was in transit or in the buffer may be dropped and not indexed.