When a user is assignedmultiple rolesin Splunk and each has a defined srchFilter, Splunk combines these filters using alogical ANDoperation. This ensures that the user can only search within the intersection of constraints imposed by each role.
From Splunk Docs:
"If a user has multiple roles assigned and multiple roles specify srchFilter, Splunk softwareANDs the filters together."
- Source: Splunk Documentation - authorize.conf
Let's break it down:
* role_A specifies: sourcetype!=json AND index=main
* role_B specifies: sourcetype=csv
To evaluate the effective search filter for the user, Splunk willANDthe two conditions:
(sourcetype=csv) AND (sourcetype!=json AND index=main)
This means the user's search is limited to events where:
* sourcetype=csv (from role_B)
* sourcetype!=json AND index=main (from role_A)
Combining them together logically:
srchFilter = ((sourcetype=csv) AND (sourcetype!=json AND index=main))
This is exactly what is shown inOption A.
Reference:
authorize.conf - Splunk Admin Manual

This option corresponds to the file path "$SPLUNK_HOME/etc/apps/splunk_TA_nginx/local/inputs.conf".
This is the configuration file that the user needs to edit to ingest the NGINX access logs to ensure it remains unaffected after upgrade. This is explained in the Splunk documentation, which states:
The local directory is where you place your customized configuration files. The local directory is empty when you install Splunk Enterprise. You create it when you need to override or add to the default settings in a configuration file. The local directory is never overwritten during an upgrade.

Setting: ignoreOlderThan = <time_window> Description: "Causes the input to stop checking files for updates if the file modification time has passed the <time_window> threshold." Default: 0 (disabled) Reference: https://docs.splunk.com/Documentation/Splunk/8.0.5/Data/ Monitorfilesanddirectorieswithinputs.conf

Using the provided DUO/Splunk reference URLhttps://duo.com/docs/splunk
Scroll down to the Network Diagram section and note the following 6 similar steps
1 - SPlunk connection initiated
2 - Primary authentication
3 - Splunk connection established to Duo Security over TCP port 443
4 - Secondary authentication via Duo Security's service
5 - Splunk receives authentication response
6 - Splunk session logged in.

https://docs.splunk.com/Documentation/Splunk/latest/Admin/Outputsconf
# Compression
#
# This example sends compressed events to the remote indexer.
# NOTE: Compression can be enabled TCP or SSL outputs only.
# The receiver input port should also have compression enabled.
[tcpout]
server = splunkServer.example.com:4433
compressed = true