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One thing is for certain: Implementing Splunk will transform your business and take it to the next level. But, the question is do you possess the skills to be a Splunker? If yes, then prepare yourselves for the most gruesome job interview because the competition is intense. You can start by going through the most common Splunk interview questions which are mentioned in this blog.
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The questions covered in this blog post have been shortlisted after collecting inputs from Splunk certification training experts to help you ace your interview. In case you want to learn the basics of Splunk then, you can start off by reading the first blog in my Splunk tutorial series: What Is Splunk? All the best!
This question will most likely be the first question you will be asked in any Splunk interview. You need to start by saying that:
Splunk is a platform which allows people to get visibility into machine data, that is generated from hardware devices, networks, servers, IoT devices and other sources.
Splunk is used for analyzing machine data because of following reasons:
|Business Insights||Splunk understands the trends, patterns and then gains the operational intelligence from the machine data which in turn help in taking better informed business decisions.|
|Operational Visibility||Using the machine data Splunk obtains an end-to-end visibility across operations and then breaks it down across the infrastructure.|
|Proactive Monitoring||Splunk uses the machine data to monitor systems in the real time which helps in identifying the issues, problems and even attacks.|
|Search & Investigation||Machine data is also used to find and fix the problems, correlate events across multiple data sources and implicitly detect patterns across massive sets of data by Splunk.|
To learn more about this topic, you can read this blog: What Is Splunk?
Splunk Architecture is a topic which will make its way into any set of Splunk interview questions. As explained in the previous question, the main components of Splunk are: Forwarders, Indexers and Search Heads. You can then mention that another component called Deployment Server(or Management Console Host) will come into the picture in case of a larger environment. Deployment servers:
Making use of deployment servers is an advantage because connotations, path naming conventions and machine naming conventions which are independent of every host/machine can be easily controlled using the deployment server.
This is a sure-shot question because your interviewer will judge this answer of yours to understand how well you know the concept. The Forwarder acts like a dumb agent which will collect the data from the source and forward it to the Indexer. The Indexer will store the data locally in a host machine or on cloud. The Search Head is then used for searching, analyzing, visualizing and performing various other functions on the data stored in the Indexer.
You can find more details about the working of Splunk here: Splunk Architecture: Tutorial On Forwarder, Indexer And Search Head.
This kind of question is asked to understand the scope of your knowledge. You can answer that question by saying that Splunk has a lot of competition in the market for analyzing machine logs, doing business intelligence, for performing IT operations and providing security. But, there is no one single tool other than Splunk that can do all of these operations and that is where Splunk comes out of the box and makes a difference. With Splunk you can easily scale up your infrastructure and get professional support from a company backing the platform. Some of its competitors are Sumo Logic in the cloud space of log management and ELK in the open source category. You can refer to the below table to understand how Splunk fares against other popular tools feature-wise. The detailed differences between these tools are covered in this blog: Splunk vs ELK vs Sumo Logic.
This is another frequently asked Splunk interview question which will test the candidate’s hands-on knowledge. In case of small deployments, most of the roles can be shared on the same machine which includes Indexer, Search Head and License Master. However, in case of larger deployments the preferred practice is to host each role on stand alone hosts. Details about roles that can be shared even in case of larger deployments are mentioned below:
You can say that the benefits of getting data into Splunk via forwarders are bandwidth throttling, TCP connection and an encrypted SSL connection for transferring data from a forwarder to an indexer. The data forwarded to the indexer is also load balanced by default and even if one indexer is down due to network outage or maintenance purpose, that data can always be routed to another indexer instance in a very short time. Also, the forwarder caches the events locally before forwarding it, thus creating a temporary backup of that data.
Look at the below image which gives a consolidated view of the architecture of Splunk. You can find the detailed explanation in this link: Splunk Architecture: Tutorial On Forwarder, Indexer And Search Head.
License master in Splunk is responsible for making sure that the right amount of data gets indexed. Splunk license is based on the data volume that comes to the platform within a 24hr window and thus, it is important to make sure that the environment stays within the limits of the purchased volume.
Consider a scenario where you get 300 GB of data on day one, 500 GB of data the next day and 1 terabyte of data some other day and then it suddenly drops to 100 GB on some other day. Then, you should ideally have a 1 terabyte/day licensing model. The license master thus makes sure that the indexers within the Splunk deployment have sufficient capacity and are licensing the right amount of data.
In case the license master is unreachable, then it is just not possible to search the data. However, the data coming in to the Indexer will not be affected. The data will continue to flow into your Splunk deployment, the Indexers will continue to index the data as usual however, you will get a warning message on top your Search head or web UI saying that you have exceeded the indexing volume and you either need to reduce the amount of data coming in or you need to buy a higher capacity of license.
Basically, the candidate is expected to answer that the indexing does not stop; only searching is halted.
If you exceed the data limit, then you will be shown a ‘license violation’ error. The license warning that is thrown up, will persist for 14 days. In a commercial license you can have 5 warnings within a 30 day rolling window before which your Indexer’s search results and reports stop triggering. In a free version however, it will show only 3 counts of warning.
Knowledge objects can be used in many domains. Few examples are:
Physical Security: If your organization deals with physical security, then you can leverage data containing information about earthquakes, volcanoes, flooding, etc to gain valuable insights
Application Monitoring: By using knowledge objects, you can monitor your applications in real-time and configure alerts which will notify you when your application crashes or any downtime occurs
Network Security: You can increase security in your systems by blacklisting certain IPs from getting into your network. This can be done by using the Knowledge object called lookups.
Employee Management: If you want to monitor the activity of people who are serving their notice period, then you can create a list of those people and create a rule preventing them from copying data and using them outside
Easier Searching Of Data: With knowledge objects, you can tag information, create event types and create search constraints right at the start and shorten them so that they are easy to remember, correlate and understand rather than writing long searches queries. Those constraints where you put your search conditions, and shorten them are called event types.
These are some of the operations that can be done from a non-technical perspective by using knowledge objects. Knowledge objects are the actual application in business, which means Splunk interview questions are incomplete without Knowledge objects. In case you want to read more about the different knowledge objects available and how they can be used, read this blog: Splunk Tutorial On Knowledge Objects
This is a common question aimed at candidates appearing for the role of a Splunk Administrator. Alerts can be used when you want to be notified of an erroneous condition in your system. For example, send an email notification to the admin when there are more than three failed login attempts in a twenty-four hour period. Another example is when you want to run the same search query every day at a specific time to give a notification about the system status.
Different options that are available while setting up alerts are:
You can find more details about this topic in this blog: Splunk alerts.
Workflow actions is one such topic that will make a presence in any set of Splunk Interview questions. Workflow actions is not common to an average Splunk user and can be answered by only those who understand it completely. So it is important that you answer this question aptly.
You can start explaining Workflow actions by first telling why it should be used.
Once you have assigned rules, created reports and schedules then what? It is not the end of the road! You can create workflow actions which will automate certain tasks. For example:
The screenshot below shows the window where you can set the workflow actions.
Data models are used for creating a structured hierarchical model of your data. It can be used when you have a large amount of unstructured data, and when you want to make use of that information without using complex search queries.
A few use cases of Data models are:
On the other hand with pivots, you have the flexibility to create the front views of your results and then pick and choose the most appropriate filter for a better view of results. Both these options are useful for managers from a non-technical or semi-technical background. You can find more details about this topic in this blog: Splunk Data Models.
Questions regarding Search Factor and Replication Factor are most likely asked when you are interviewing for the role of a Splunk Architect. SF & RF are terminologies related to Clustering techniques (Search head clustering & Indexer clustering).
There will be a great deal of events coming to Splunk in a short time. Thus it is a little complicated task to search and filter data. But, thankfully there are commands like ‘search’, ‘where’, ‘sort’ and ‘rex’ that come to the rescue. That is why, filtering commands are also among the most commonly asked Splunk interview questions.
Search: The ‘search’ command is used to retrieve events from indexes or filter the results of a previous search command in the pipeline. You can retrieve events from your indexes using keywords, quoted phrases, wildcards, and key/value expressions. The ‘search’ command is implied at the beginning of any and every search operation.
Where: The ‘where’ command however uses ‘eval’ expressions to filter search results. While the ‘search’ command keeps only the results for which the evaluation was successful, the ‘where’ command is used to drill down further into those search results. For example, a ‘search’ can be used to find the total number of nodes that are active but it is the ‘where’ command which will return a matching condition of an active node which is running a particular application.
Sort: The ‘sort’ command is used to sort the results by specified fields. It can sort the results in a reverse order, ascending or descending order. Apart from that, the sort command also has the capability to limit the results while sorting. For example, you can execute commands which will return only the top 5 revenue generating products in your business.
Rex: The ‘rex’ command basically allows you to extract data or particular fields from your events. For example if you want to identify certain fields in an email id: email@example.com, the ‘rex’ command allows you to break down the results as abc being the user id, edureka.co being the domain name and edureka as the company name. You can use rex to breakdown, slice your events and parts of each of your event record the way you want.
Lookup command is that topic into which most interview questions dive into, with questions like: Can you enrich the data? How do you enrich the raw data with external lookup?
You will be given a use case scenario, where you have a csv file and you are asked to do lookups for certain product catalogs and asked to compare the raw data & structured csv or json data. So you should be prepared to answer such questions confidently.
Lookup commands are used when you want to receive some fields from an external file (such as CSV file or any python based script) to get some value of an event. It is used to narrow the search results as it helps to reference fields in an external CSV file that match fields in your event data.
An inputlookup basically takes an input as the name suggests. For example, it would take the product price, product name as input and then match it with an internal field like a product id or an item id. Whereas, an outputlookup is used to generate an output from an existing field list. Basically, inputlookup is used to enrich the data and outputlookup is used to build their information.
‘Eval’ and ‘stats’ are among the most common as well as the most important commands within the Splunk SPL language and they are used interchangeably in the same way as ‘search’ and ‘where’ commands.
|Stats is a reporting command which is used to present data in a tabular format.|
Chart displays the data in the form of a bar, line or area graph. It also gives the capability of generating a pie chart.
|Timechart allows you to look at bar and line graphs. However, pie charts are not possible.|
|In Stats command, you can use multiple fields to build a table.||In Chart, it takes only 2 fields, each field on X and Y axis respectively.|
In Timechart, it takes only 1 field since the X-axis is fixed as the time field.
This is the kind of question which only somebody who has worked as a Splunk administrator can answer. The answer to the question is below.
There are about 5 fields that are default and they are barcoded with every event into Splunk.
They are host, source, source type, index and timestamp.
File precedence is an important aspect of troubleshooting in Splunk for an administrator, developer, as well as an architect. All of Splunk’s configurations are written within plain text .conf files. There can be multiple copies present for each of these files, and thus it is important to know the role these files play when a Splunk instance is running or restarted. File precedence is an important concept to understand for a number of reasons:
To determine the priority among copies of a configuration file, Splunk software first determines the directory scheme. The directory schemes are either a) Global or b) App/user.
When the context is global (that is, where there’s no app/user context), directory priority descends in this order:
When the context is app/user, directory priority descends from user to app to system:
You can extract fields from either event lists, sidebar or from the settings menu via the UI.
The other way is to write your own regular expressions in props.conf configuration file.
As the name suggests, Search time field extraction refers to the fields extracted while performing searches whereas, fields extracted when the data comes to the indexer are referred to as Index time field extraction. You can set up the indexer time field extraction either at the forwarder level or at the indexer level.
Another difference is that Search time field extraction’s extracted fields are not part of the metadata, so they do not consume disk space. Whereas index time field extraction’s extracted fields are a part of metadata and hence consume disk space.
Data coming in to the indexer is stored in directories called buckets. A bucket moves through several stages as data ages: hot, warm, cold, frozen and thawed. Over time, buckets ‘roll’ from one stage to the next stage.
The bucket aging policy, which determines when a bucket moves from one stage to the next, can be modified by editing the attributes in indexes.conf.
Summary index is another important Splunk interview question from an administrative perspective. You will be asked this question to find out if you know how to store your analytical data, reports and summaries. The answer to this question is below.
The biggest advantage of having a summary index is that you can retain the analytics and reports even after your data has aged out. For example:
But the limitations with summary index are:
That is the use of Summary indexing and in an interview, you are expected to answer both these aspects of benefit and limitation.
You might not want to index all your events in Splunk instance. In that case, how will you exclude the entry of events to Splunk.
An example of this is the debug messages in your application development cycle. You can exclude such debug messages by putting those events in the null queue. These null queues are put into transforms.conf at the forwarder level itself.
If a candidate can answer this question, then he is most likely to get hired.
Time zone is extremely important when you are searching for events from a security or fraud perspective. If you search your events with the wrong time zone then you will end up not being able to find that particular event altogether. Splunk picks up the default time zone from your browser settings. The browser in turn picks up the current time zone from the machine you are using. Splunk picks up that timezone when the data is input, and it is required the most when you are searching and correlating data coming from different sources. For example, you can search for events that came in at 4:00 PM IST, in your London data center or Singapore data center and so on. The timezone property is thus very important to correlate such events.
Splunk Apps are considered to be the entire collection of reports, dashboards, alerts, field extractions and lookups.
Splunk Apps minus the visual components of a report or a dashboard are Splunk Add-ons. Lookups, field extractions, etc are examples of Splunk Add-on.
Any candidate knowing this answer will be the one questioned more about the developer aspects of Splunk.
You need to assign colors to charts while creating reports and presenting results. Most of the time the colors are picked by default. But what if you want to assign your own colors? For example, if your sales numbers fall below a threshold, then you might need that chart to display the graph in red color. Then, how will you be able to change the color in a Splunk Web UI?
You will have to first edit the panels built on top of a dashboard and then modify the panel settings from the UI. You can then pick and choose the colors. You can also write commands to choose the colors from a palette by inputting hexadecimal values or by writing code. But, Splunk UI is the preferred way because you have the flexibility to assign colors easily to different values based on their types in the bar chart or line chart. You can also give different gradients and set your values into a radial gauge or water gauge.
Now this question may feature at the bottom of the list, but that doesn’t mean it is the least important among other Splunk interview questions.
Sourcetype is a default field which is used to identify the data structure of an incoming event. Sourcetype determines how Splunk Enterprise formats the data during the indexing process. Source type can be set at the forwarder level for indexer extraction to identify different data formats. Because the source type controls how Splunk software formats incoming data, it is important that you assign the correct source type to your data. It is important that even the indexed version of the data (the event data) also looks the way you want, with appropriate timestamps and event breaks. This facilitates easier searching of data later.
For example, the data maybe coming in the form of a csv, such that the first line is a header, the second line is a blank line and then from the next line comes the actual data. Another example where you need to use sourcetype is if you want to break down date field into 3 different columns of a csv, each for day, month, year and then index it. Your answer to this question will be a decisive factor in you getting recruited.
I hope this set of Splunk interview questions will help you in preparing for your interview. You can check out the different job roles, a Splunk skilled professional is liable for by reading this blog on Splunk Careers. Also, we have the video on Splunk Interview Questions by an expert which can help you further. Do take a look and let us know if this helped in your interview preparation.
This Splunk Tutorial video will help you prepare for your next Splunk interview. We have curated a list of Top questions that are asked in Splunk job interviews. We have also included the best answers to these questions.
In case you want to skill up with Splunk and upgrade your resume, you can check out Edureka’s interactive, live-online Splunk certification training course which comes with 24*7 support to guide you throughout your learning period.
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