WebLogic Administrator Interview Questions

Q: What do you mean by weighted based server instance? How do you configure it?

Ans: The Weblogic Servers in a cluster environment could be routed in 4 ways ROUND-ROBINWEIGHT-BASEDRANDOM We can control the incoming requests using weights increase or decrease, So, that all the request will goes to one particular managed server only that too possible.

Q: How to enable EJB available to servlet? asume servlet on apache, ejb on Weblogic cluster.

Ans:Any external access to EJB is not allowed. if the apache webserver already configure as front-end. then we need to look up by JNDI tree.

Q: What is the silent mode installation file contains root element? When do you require this mode of installation?

Ans:The root element in silent.xml is <install>This kind of mode usually required in two different situations.

Situation1 : Weblogic clusters could be installed/implemented only on homogenous environments. If cluster1 is constructed with MgdServer1, MgdServer2if one server isusing Weblogic 7 environment and other one on Weblogic 8.1 or higher this is not allowed.

Situation 2: When one huge project is migrated from one physical location to other, Where the Application specialist must have the similar environment as the Production Server had. To prepare Development work with similar kind environment we shall install on First system same as Production Server rest of the developers systems could be installed with silent mode.

Q: Why do you need multicast address in Clustering?

Ans: The Multicast address is must for clustering, If server instance need to join the cluster it will use multicast address. The Administrator server handles the web/resource request which is incoming to the Weblogic server then the admin server will send poll messages for availability to handle the current incoming request by which member server in the cluster with multicasting. The multicast address should not conflict with the Network configurations on every member server. The range of multicast IP address is : 224.0.0.0 to 239.255.255.255.The admin server sends a TTL (Time to Leave) packet,which will acknowledges the readiness of a managed server. If more than one member server is available then it will choose the member server with first come first server bases.

Q: What are all the ant command options?

Ans:To view all options of ant command is simple, just use the following command :prompt> ant -helpNote: This will work on Unix and Windows too iff PATH is pointing to ant specific jars

Q: What is the ant version last you used? How to get it??

Ans: I am using Weblogic 8.1 it internally provides ant support which is 1.5.6 version.To get this simply use : prompt> ant -version

Q: How do you config eclipse with Weblogic?

Ans:Weblogic version wise plug-ins are available for free download sites. Eg: lomboz tool it is a very simple tool, my experience is that deployment on WL is very few steps required.Just we need to copy the plug-in extracted to eclipse/plug-ins folder. Here we need to follow the correct J2EE specification for easy deployments of application.

Q: what is the source to identifying the Connection pool failure? What is the remedy?

Ans: In WL 7/8 to identify the connection pool failure we have 3 options: 1.The Connection pool hosting Server instance healthchecking by Monitoring tab where we need to find the idle thread availability.2. Checking in the weblogic log of that corresponding server instance. Usually we get broken pipe Exception.This could be generated due to overload on connection pool. To resolve we can tune the execute threads for the corresponding server instance.3. Look for Thread dump and identify the which thread is doing which task execution?

Q: What is thread dump? Why we need it? How do we get it?

Ans:Thread dump concept is used only by Admin users who operates the production server; it is the dump of the behavior of the WebLogic server instance’s execute threads.When the thread dumps helpful? If WLS execute threads misbehaving due to following reasonsMaybe you just need more threads. Maybe you need some of your application to use a different queue. Maybe your application needs tuning.There is a need of trouble shoots the issues due to various reasons: 1. Requests overloaded2. Connection Pool fails3. File cannot read/write for any application (which might be xml file too)4.Queues are overloadedIn windows CTRL + Break , There is another common method to get thread dump:a) Open a cmd window (in Windows) or shell (in Unix/Linux)b) Set the proper java path and add weblogic.jar to the classpathc) Run the following command script :prompt >java weblogic.Admin -url t3://host:port -username weblogic -password weblogic THREAD_DUMP Here please replace with the correct host, port number, username and password. You can get the thread dump from the standard output.

Q: What is the procedure for Queues config? How to make them to free?

Ans:The Queues configuration requires persistence storage which could be a File on operating system or a Database. The queue configuration requires JMSConnectionFactory, JMSServer, Queue or topic as per the need for the application created using the Weblogic Administration console.

Q: What is the architecture you follow for your current project?

Ans: DMZ ( webserver-weblogic-database) with Multi- tiered architecture where in the first level of request could be handled by CISCO CSS to Apache webserver instances then next to WebLogic domains as per the application requirements the Oracle database is configured thru connecton pools. going forward Middle ware server as Tuxedo server connecting to Mainframe based Database Server where the billing system resides.

Q: Do you required JDK/JRE for installing a WL Domain?

Yes, JRE is required to run the Configuration Wizard in GUI. if the domain configuration is in the console mode or silent mode it is not required. Some Unix flavour OS does not have JRE in built so we need to install JDK/JRE before the WL domain creation. It is one of the pre-requisite for domain creation.

Q: What is the basic requirement for starting a Weblogic server?

Ans:The basic requirement for starting WLS is ... If you need to start service like web application/enterprise application we must start the WebLogic server instances. These services requires the server to be running state then only they can serve the client request. The server instances would be one of the targets for deployment of services. If I have a jar file and a war file how do you design your WebLogic server configuration?That depends on the version dmconf, config executable file(s) which gives us configuration wizard to configure the Weblogic server(s) on the domain and with option to create cluster env.

Q: Why do you feel that there is need for webserver like Apache as frontend before to WebLogic?

The Weblogic server alone acts as group of server instances if one of the request might lead to down the server then whole applicatons goes down. in the safer sinario we use Apache as sheld from Web. Apache is most powerful in tranfering the Images, CSS, Html related scripts on the fly... the apache just hold the images or .css or .js files in the cache when new web client request will be executed faster compare to Weblogic webserver

                                   WIPRO AND ORACLE

1. Describe yourself about your daily activities @ work

2. What is the way to find the impact on the database connection changes on a server instance?

3. How do you identify the Server instance is overloaded? (Idle Threads)

4. How do you connect to ORACLE RAC with WebLogic Connection Pool?

5. How do you do create Thread Dump?(kill -3 refer above)

6. How the message are generate into the monitoring tool?

7. Usually which language you prefer to write code like options are Jacl/Python/?

8. What is JVM?

9. What is the EJB?

10.How do you measure the heap size of a WebLogic server?

                                     Basic Unix

1. How do you copy files from onemachine to other? (scp/sftp/ftp)

2. How do you take the backup of the files to tape drive?

3. How do you create a directory? (mkdir)

4. vi - how do you search for a word?  : name work

5. vi - how do you replace words? n word

6. vi - save a file how? (:wq or :w or ZZ)

7. Which scripting shell you have used?

8. How do you export a env variable in a shell script?

9. How do you check the script is already existing or not?

10. How do watch the memory size for a the mounted devices ? (df -k)

Database/Oracle

1. How do you connect to Oracle database? discuss on connection pool configuration?.

2.How do you get the total count of the records in a table?

3.How do you delete a row in a table?

                                              (Verizon)

1. You need to handle whole and sole responsibilities to handle WebLogic Admin activities are you ready to accept?

2. What is the experiance with WebLogic Administration activities you do in last project/current project?

3. What is a cluster? What is High Availability and Fail over?

4. What is the major difference between managed server and admin server?

5. What is the difference between Connection Pool and datasource?

6. Do the user can use Connection pool in their program?

7. How do you configure ORACLE RAC env to WebLogic Connection Pool? What are the conditions applied for this?

8. How do you use weblogic.Admin tool? what for it is used?

9. What is the Thread Dump? when do you need it? What do you analyze from thread dumps?

10. What is a web server? how it is different from Application server?

11. What is level of comfort in architecturing/designing?

                                        Second round:

1. What do you mean by multipool? how does it differ from connection pools?

2. Have ever worked on tuning of the weblogic?

3. Have you ever installed weblogic on UNIX env? Have you installed from a CD?

4. Why do you choose Type-4 driver instead of Type-2? What are the features of type-4 driver?

5. When do you go for Weblogic jDriver? What advantages with jDriver?

6. What is the recent Exception you had faced in troubleshooting activity?

7. Do you ever experianced the Webserver configuration for Weblogic?

8. Do you have the steps to implement IIS webserver for Weblogic 9 Server?

9. Do you have any idea about WLI, WebLogic Portals?

10. What is the difference in normal Weblogic JMS and WLI JMS queues?

11. What kind of preventions you take for troubleshooting? How do you proceed in the finding the culprit?

                              Scripting Related Questions

1. Do you know how to write a script?

2. Have you ever written scheduled jobs?

3. Have you ever written rc scripts?

4. Which version of Solaris you have been worked?

5. If you have given high severity script to update how do you do that?

Simple take the help of the team members. If the solutions is not found I will look into internet group/blogs thru search engine.

6. Have you ever written any schedule scripts?I got chance to work on scheduled script only few times. I said myself very little experience in using crontab.

7. How do you assign a cron job?

Ans: Using crontab command followed by the cron scheduler file which says what script/program to be executed at what time.

 

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