for a wide variety of logs please check out this site https://ossec-docs.readthedocs.io/en/latest/log_samples . you can then use eventgen app in splunk to generate runtime logs based off these samples.
these tutorial files are great? related to this, is there any SQL server database sample data which we can use to work with Splunk?
I setup a small lab at home on my vmware server containing several linux servers - proxy, dns, http, mysql, postfix etc.
Sent all of my router info to Splunk through udp to capture firewall events and potential attacks.
Also forwarded a few Windows laptops to Splunk which generates a bunch of data.
Once you point your laptops to browse the internet through your proxy server and dns server you will have plenty of data.
Just get creative with data you are already generating and capture it.
Good Luck!
I would install the Splunk Reference App -PAS and AUTH0. These contain example data set for Splunk Developer Guidance which uses the Event Gen app. I use it all the time to fake data.
Dev Guide
Splunk Code Repo
Splunk Test Repo
Eventgen app on Splunk Base
Another great data set is the Airline On-Time data from the US dept of transportation.
http://www.transtats.bts.gov/Tables.asp?DB_ID=120
That's 30 years worth of airline data (so make sure, when you index it you have adjusted the frozenTimePeriodInSecs in your indexes.conf so that it doesn't just roll stuff out of cold when it hits 6 years. (I learned that the hard way!)
It's not a simple data set so there are some challenges, but it's quite extensive... and really fascinating.
If you step through the Search Tutorial, it includes a zip file of sample data you can use to learn the basics of searching and reporting. That is most people's entry into the world of Splunk.
A couple of years back there was a Splunk blog posting about an easy way to generate sample data sets.
And Amazon has a list of public data sets available in AWS.
But I recommend starting with the tutorial data.
You can download one of the facebook or twitter apps and get a stream of data to play with but even better, you can create a free cloud sandbox and there is a ton of fake data streams already there. Just go through the tutorial and you will see how to access it:
https://www.splunk.com/getsplunk/onlinesandbox
Splunk also provides a tool for generating fake streams of data called eventgen
and there is a new rewrite of this called gogen
(google on github, I think).