Apache Tomcat Interview Questions And Answers

41. What is the servlet container life cycle?
Answer: 1 Servlet life cycle
1 Servlet life cycle
A servlet life cycle can be defined as the entire process from its creation until the destruction.
Life cycle steps followed by a servile
The servlet receives a request from a client through one of its connectors then is initialized by calling the init() method.
The servlet calls service() method to process a client’s request and send the response.
The servlet is terminated by calling the destroy() method.
The servlet is garbage collected by the garbage collector of the JVM.

42. What is a connector and why it is used in Tomcat?
Answer: The Apache Tomcat Connectors project is a part of the Tomcat project and provides web server plug-ins to connect web servers with Tomcat and other back-ends.
The supported web servers are:
The Apache HTTP Server with a plugin named mod_jk.
Microsoft IIS with a plugin named ISAPI redirector.
The iPlanet Web Server with a plugin named NSAPI redirector.

43. What is the server?
Answer: A Server element represents the entire Catalina servlet container. Therefore, it must be the single outermost element in the conf/server.xml configuration file. Its attributes represent the characteristics of the servlet container as a whole.

44. What is the server server.xml configuration file?
Answer: The server.xml file is Tomcat main configuration file, and it is responsible for specifying the Tomcat configuration on startup.

45. How to deploy War web applications in Tomcat?
Answer: You can drop the WAR file inside the web apps folder or use the Tomcat manager to deploy War files. ( tableau online training ) 

46. Can Tomcat use SSL?
Answer: Yes, you need to make additional configurations to make Tomcat use SSL. In resume, you need to do these tasks
Generate Keystore
Add a connector in server.xml
Restart Tomcat

47. What is virtual hosting?
Answer: This is a way of hosting more than one domain names on one server using a single IP address. This way, the single server can share its resources which may include memory, processor cycles among others to ensure its efficient use.

48. What is Document Root?
Answer: DocumentRoot directive is the configuration where you can specify the folder location from where the static files will be served. It’s also called as WebRoot.

49. What is a mod_evasive module?
Answer: mod_evasive is a third-party module that performs one simple task and performs it very well. It detects when your site is receiving a Denial of Service (DoS) attack and it prevents that attack from doing as much damage. mod_evasive detects when a single client is making multiple requests in a short period of time and denies further requests from that client. The period for which the ban is in place can be very short because it just gets renewed the next time a request is detected from that same host.

50. What are the log files generated by Apache?
Answer: There are two popular log files created;
access.log – all request details with the status code
error.log – capture all the errors within apache or connecting in the backend.

51. What tool do you use for log analysis?
Answer: You got to speak the truth but to give you an idea you can use GoAccess, SumoLogic or few mentioned here.

52. What is mod_vhost_alias?
Answer: It allows hosting multiple sites on the same server via simpler configurations.

53. what is a difference between Apache and Nginx web server?
Answer: Both are categorized as a Web Server and here are some of the main differences.
Nginx is an event-based web server where Apache is process based
Nginx is known for better performance than Apache
Apache supports a wide range of OS where Nginx doesn’t support OpenVMS and IBMi
Apache has a large number of modules integration with backend application server where Nginx is still catching up
Nginx is lightweight and capturing the market share rapidly. If you are new to Nginx, then you may be interested in checking out my articles on Nginx.

54. What is the difference between Worker and Prefork MPM?
Answer: Both MPMs, Worker and prefork has their own mechanism to work with Apache. It totally depends on you that in which mode you want to start your Apache.
Basic difference between Worker and MPM is in their process of spawning the child process. In the Prefork MPM, a master httpd process is started and this master process starts manages all other child processes to serve client requests. Whereas, In the worker MPM one httpd process is active, and it uses different threads to serve client requests.
Prefork MPM uses multiple child processes with one thread each, where worker MPM uses multiple child processes with many threads each.
Connection handling in the Prefork MPM, each process handles one connection at a time, whereas in the Worker MPM each thread handles one connection at a time.
Memory footprints Prefork MPM Large memory footprints, where Worker has smaller memory footprints.

55. What is the main configuration file of the Apache server?
Answer: The Apache Web Server is the most commonly used web server. Before going for any interview involving web servers, make sure to go through these apache interview questions. This way you get an idea of what Apache entails. You can share your thoughts in this article with regards to the apache interview questions and the way answers are provided. Feel free to suggest more issues and solutions for the same to help others learn more about the Apache webserver. ( hadoop training online )

56. What do you mean by a valid ServerName directive?
Answer: The DNS system is used to associate IP addresses with domain names. The value of ServerName is returned when the server generates a URL. If you are using a certain domain name, you must make sure that it is included in your DNS system and will be available to clients visiting your site.