IIS Interviews Questions and Answers

1. What is the Role of IIS ?

Visual studio having It own ASP.NET Engine which is capable enough to run Asp.net web application from visual studio. So we just click on Run button to start the application.
Now this is the scenarios of local environment. But If we want to host it on server from where all user can access the sites then IIS comes into the picture.

IIS provides a redesigned WWW architecture that can help you achieve better performance, reliability, scalability, and security for our Web sites. IIS can support following Protocol HTTP/HTTPS, FTP, FTPS, SMTP Etc. We need to host the site on IIS, when request comes from client it first hits the IIS Server, then the server passed it to ASP.NET worker process to execute. Then the response also passes to client via IIS itself.
Note only Hosting of Site we can create our FTP Server, SMTP Server using IIS itself.
There are different version of IIS available like 5.1, 6.0, 7.0 etc

2. What are the additional or enhanced security features in IIS 7.5?
Following are the features
Client certificate mapping
IP security
Request filtering
URL authorization

3. What are the modules in IIS 7.0?
Ans. IIS 7.0 is an modular architecture, few of the modules are
1. security module
2. content module
3. compression module
4. caching module
5. logging and diagnostic module

4. What are the different version on IIS that you have worked on ?

Before answering this question you need to know what are the different IIS version is available in different OS. Below is the list of IIS version with different Operating system.
Windows Server 2008 – Windows Vista – Home Premium/ Ultimate- IIS 7.0
Windows Server 2003- IIS 6.0
Windows XP Professional – IIS 5.1
Now based on your working experience you can say that you have worked on IIS 5.1 and 6.0 or only IIS 7. Etc.
Now, the next question that can asked after answering this question is “what is the difference between them ? ” – Well I will come with this later.

5. What is Application Pool in IIS ?

Before Giving the Definition : you can say like this, Concept of Application pool has from IIS 6.0 .
Application pools are used to separate sets of IIS worker processes that share the same configuration and application boundaries. Application pools used to isolate our web application for better security, reliability, and availability and performance and keep running with out impacting each other . The worker process serves as the process boundary that separates each application pool so that when one worker process or application is having an issue or recycles, other applications or worker processes are not affected.
One Application Pool can have multiple worker process Also.

6. What is ISAPI in IIS?
Ans. ISAPI is an open specification introduced by microsoft.
It is faster and more flexible than CGI for extending IIS.

7. What is the Role of IIS ?

Visual studio having It own ASP.NET Engine which is capable enough to run Asp.net web application from visual studio. So we just click on Run button to start the application.Now this is the scenarios of local environment. But If we want to host it on server from where all user can access the sites then IIS comes into the picture. IIS provides a redesigned WWW architecture that can help you achieve better performance, reliability, scalability, and security for our Web sites. IIS can support following Protocol HTTP/HTTPS, FTP, FTPS, SMTP Etc. We need to host the site on IIS, when request comes from client it first hits the IIS Server, then the server passed it to ASP.NET worker process to execute. Then the response also passes to client via IIS itself.Note only Hosting of Site we can create our FTP Server, SMTP Server using IIS itself.There are different version of IIS available like 5.1, 6.0, 7.0 etc

8. What are the different security settings available in IIS ?

Below are the commonly used IIS Security settings

1 Anonymous
2 Integrated Windows Authentication
3. Basic Authentication
4. Digest Authentication
5. Passport Authentication

9. What is the Name of Default Application Pool in IIS ?

Default application pool named : DefaultAppPool

10.  What is the Role of Http.Sys in IIS ?

HTTP.SYS is the kernel level components of IIS. All client request comes from client hit the HTTP.Sys of Kernel level. HTTP.SYS then makes a queue for each and every request for each and individual application pool based on the request.Whenever we create any application pool IIS automatically registers the pool with HTTP.SYS to identify the particular during request processing.

11. What are the different types of Identity available in IIS 6.0 ?>

IIS having three different Identity.
1. Local System
2. Local Services
3. NetworkServices

12. Name of default Identity of IIS6.0

Default Identity of IIS 6.0 is NetworkServices .
Which is having very minimum rights on your system. The user can only have the read access of the site.

13. What exactly means HTTP.sys in IIS?
Ans. HTTP.sys is known as “HTTP Protocol Stack” or “Http Listener Process”
• It is Implemented as a kernel-mode device driver
• It is core component to receive and serve HTTP requests and passing them off to the worker processes
• When you create a Web site, IIS registers the site with HTTP.sys
• Other than retrieving a stored response from its internal cache,
HTTP.sys does not process the requests that it receives.

16. What is Recycling of Application Pool ?

ecycling Application pool means recycle the Worker process (w3wp.exe ) and the memory used for the web application.
There are two types of recycling related with Application pool

1. Recycling Worker Process – Predefined Settings
2. Recycling Worker Process – Based on Memory

15. What are ISAPI filters in IIS?
Ans.
• ISAPI filters are DLL files that can be used to modify and enhance the functionality provided by IIS
• ISAPI filters always run on an IIS server, filtering every request until they find one they need to process
• Mostly used for Authentication and Encryption of the i/p or o/p data for a site locally or all the apps globally

16. What are Application pools in IIS?
Ans. Group of Web Applications and Web Sites are called Application Pools.

17. What are the main layers of IIS Architecture ?

IIS having mainly two layer Kernel Mode and User Mode

Below are the subsection of both of them.
1. Kernel Mode
o HTTP.SYS
2. User Mode
o Web Admin Service
o Virtual Directory
o Application Pool

18. What is the Role of Http.Sys in IIS ?

HTTP.SYS is the kernel level components of IIS. All client request comes from client hit the HTTP.Sys of Kernel level. HTTP.SYS then makes a queue for each and every request for each and individual application pool based on the request.
Whenever we create any application pool IIS automatically registers the pool with HTTP.SYS to identify the particular during request processing.

19. From where you can change the ASP.NET Version in IIS ?
This can be change from Virtual Directory properties. First open Properties of Virtual Directory > GoTo ASP.NET Version Tab.
There we can have change the ASP.NET Version.

20. What is the default user name of an anonymous login in IIS?
In IIS, an anonymous user will be given with a user name of “IUSR_MachineName “

21. How can we take back-ups in IIS Server?

Step 1 : In the IIS (inetmgr), right click on the “Computer” icon under “Internet Information  Services” . Click “All Tasks” and select “Backup/Restore Configuration”.
Step 2 : Click on button “Create backup”. Give Name for your backup file. If you want encryption enable encryption option and give UserName and Password and then click OK.

22. What is IIS metabase? And In which format IIS stors configurations?
IIS metabase is a special databse which is used to maintain the settings and configurations data for IIS. In simple term, it is a configuration base for IIS (Metabase.xml).
IIS 5.0 –> Metabse is in Binary.
IIS 6.0 & 7.5 –> Metabase is in XML.

23. What are the main components of SVCHost.exe ?

Main components for SVCHost.exe are WWW Publishing Service (W3SVC) and Windows Activation Porcess (WAP) .

W3SVC is the mediator of HTTP.SYS and Windows Activation Process. Windows Activation Process maintain the worker processes.

24. What are the different way that we can hosted site on IIS ?

We can hosted site on IIS either creating Virtual Directory through IIS manager or Using Folder Web Sharing .
Apart from that Visual studio provide some inbuilt features to host the site on IIS like using Publishing the web site , Using Copy web Tool or Creating Virtual directory during the creating the project by choosing Location as HTTP

25. How does IIS process an ASP.net request ?

When client request for an aspx pages, request comes to kernel level off IIS means to HTTP.SYS . HTTP.SYS receives the request and based on the application pool name [ Which is already registred with the HTTP.SYS ] it send the request to worker process. Windows Activation process works as mediator of them. w3wp.exe loads “aspnet_isapi.dll” files to start the HTTPRuntime HTTPRuntime creates HTTPApplication objects and all request are passed through HTTPModule and finally reached to HttpHandler . This is the request pipeline. After end of Request pipeline ASP.NET Page lifecycle starts.

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