IBM Interview Questions

These are the interview questions which asked on 17-04-09 by IBM intial round. One thing should remember by everyone, now a days all the companies who are taking WAS admins they are asking questions on O/S also, like Linux or UNIX. So be prepare for those operating systems also before attending an interview.

1. Tell me about yourself (roles and responsibilites)
2. What is the difference b/wn appserver and webserver?
3. How do u configure the plug-in file?
4. How do u configure JDBC drivers and what is meant by J2C authentication?
5. How Internet Works?

A) The Internet is a global system of interconnected computer networks that use the standardized Internet Protocol Suite (TCP/IP). It is a network of networks that consists of millions of private and public, academic, business, and government networks of local to global scope that are linked by copper wires, fiber-optic cables, wireless connections, and other technologies.
6. Explain the process of Federation?
7.How do u administrate admin console in unix?
8. what are the different types of clustering? done
9. What is the advantages of Vertical Clustering?
10. Do u have any idea or did u work with JACL scripts?
11. Where do you find the problems of a Webserver(Log file)?
12. How many types of log files are there! What are they!
13. What is log rotation policy?
14. Where do you enable the Garbage Collector?

using -verbosegc in startup command
15. How to tune an application?
16. When you will perform Thread Dump and Heap Dump?
17. What are the parameters that to pass while generating an Heap Dump?
18. How To identify that heap memory is decreasing and where?
19. Describe the real time problems that u faced in your administration career?
20. What are the major tasks you solved?
21. What is the difference between SSH and Https?
22. Why we enable SSL on webserver rather than App.Server?

A) When ever request comes to application it is start working from Webserver.

SSH

Secure Shell (SSH), sometimes known as Secure Socket Shell, is a Unix-based command interface and protocol for securely getting access to a remote computer. It is widely used by network administrators to control Web and other kinds of servers remotely. SSH is actually a suite of three utilities - slogin, ssh, and scp - that are secure versions of the earlier UNIX utilities, rlogin, rsh, and rcp. SSH commands are encrypted and secure in several ways. Both ends of the client/server connection are authenticated using a digital certificate, and passwords are protected by being encrypted.

SSH uses RSA public key cryptography for both connection and authentication. Encryption algorithms include Blowfish, DES, and IDEA. IDEA is the default.

SSH2, the latest version, is a proposed set of standards from the Internet Engineering Task Force (IETF).

How To Connect To WSadmin Console through SOAP ?

Generally we connect wsadmin console directly with soap port or rmi port.
specially if we want to check whether a particular SOAP port of dmgr is working or not, this requisition we need whenever we are federating a node to a dmgr.
The following is the command which we use to check whether a particular port is communicating or not.

wsadmin -conntype SOAP -port 8879

wsadmin -conntype RMI -port 9809

wsadmin -conntype RMI -port 2809 -user u1 -password secret1

(1.1) Issues: we got responce from users saying that they not able to receive messages from their application.

Sol : we identified that message receiver server not able to recive messages from MQ, because of File storeage failed, then we informed the same to system infrastructure team they added SAN, even though the problem not got resolved.

I am seeing some transaction timeout errors in the logs:####<21-Jul-2009 16:18:23 o'clock BST> <21cnedc313>

(1.2) Issues: JMS transaction timeout messages like this in WAS.

Sol: there are bulk number of JMS messages stored in MQ Server, when ever san got added at a time all the messages in MQ, hit the server at a time, so server is not able process that many number of requests at a time, then we increase the JTA transaction time out value from 30 to 100, this will allow more time for transaction to complete. After process all the requests we changed the transaction time out value back to 30.

(2.1) Issues: the WAS server logs are not getting generated in both the nodes. The last timestamp in the logs file is 18/07/09 15:36.The same issue has occurred few times and we have to restarted both the managed servers for the logs to be generated.

Could you please let us know what could be the reason for this issue?

Sol. The log rotation was not set properly, which I have set now. Also the log stopped in the middle of printing some debugs, which suggests that it ran out of disk space. The /IBM_profile is mounted on root partition.

(3.1) Can you please send the P2 case (TAM Test Tool not working) which came today morning to APLSUP54 and request them to check why the ?java.lang.OutOfMemoryError: unable to create new native thread? occurred.

Also mention in that case that we had taken the thread dump and is present at mps location.

Sol. This is again a native memory issue. The JVM heap allocated is 1.5 Gb (which is necessary otherwise app starts giving heap errors), which leave 512mb for native memory out of the possible 2Gb max.

This native memory is used by all the native modules like MQ or application codes creating native memory. If the native memory is not sufficient then you get OutofMemory:unable to create a new native thread error.

(4.1) We are facing problem with the WebSphere server in dybip04. We are using BEA version 8.1SP6

The Managed server is suddenly going into UNKNOWN state and when we try to restart the server

The following error is occurring::

OutOfMemoryError occured on server

Sol. I have increased the memory size to 2GB and restarted the server. The messages are being consumed now.

5.1) we are facing connection failure error, due to what causes?

Sol. Finally we found, driver there is one DB driver corrupted in it causes the issue.

Firewarll -> loadbalancer -> Webserver -> app.ser visa plugin -> hits application -> contact db to ds and

request - > firewall -> loadbalancer(split the load into multiple Webserver) -> (sitemider/ssl) webserver -> via plug in which is in the application server -> application

In side cluster jvm will respond.

How much memory tuned for your application servers in your environment?

Depend upon the application, decided by developer. Or depends on OS.

How will you login to solaris/ linux for installations?

Normally we will not use rout privileged ID for installing/configuring was applications in Linux.

Ex: empid

Su wasuser(not root privileged user) Non-route user

What are the two basic steps that admin have to do after deploying the application & before running the application?

have to regenerate the web server plug-in, copy it over to the web server machine and do a quick restart of it

1.wht is hot deployment, and where we get a chance to go for this?
Hot deployment means adding modules or additional services to the existing application or new application without stopping the application server as well as application. When an application is went to Production environment then we can't stop the application as application requests will come. So in that case we will go for hot deployment.

2.Can we access 2 different applications at once running on 2 application servers in a cluster?

If those two applications are mapped exactly on to the same cluster members, we can access for them by configuring the webserver and plug-in properly for the cluster.

3.how to enable Global Security in WAS though CUI?

To enable Global Security first we have to do
1. Select the Authentication Registry, i.e., either Local OS or LDAP.
Here we have to specify the primary administrative user name which should be present there in the registry.
2. Select the Authentication Mechanism i.e., LTPA or SWAM.
Here we have to specify the password and confirm-password.
3. Enable Global Security.
4. Save and restart the server.

4.If the app server crashes in the middle of application deployment , wht could be the reason and wht steps we have to follow?

If the server resources are less while deployment, when application requests are hitting application server due to less resources the application server will crash. If the application server crash then that time we can get thread dump.

5.During WAS ND installation, one default server "server1" creates right?can we change its name during installation?

If we are installing, in silent we can change the default server name we can change, in GUI its not possible.

Q: What is the default port for SSH server?
A: 22