IIS Interview Questions Answer

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

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.

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.

Main Point to Remember:
1. Isolation of Different Web Application
2. Individual worker process for different web application
3. More reliably web application
4. Better Performance

What is the Name of Default Application Pool in IIS ?

Though we can create new application pool IIS with different settings, but IIS having its own default application pool named : DefaultAppPool

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

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.

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

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

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.

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

For Set security permission you need to go to Virtul Directory > Right Click > Properties > Directory Security
Click on Edit Button .

What is the default authentication settings for IIS ?

Anonymous authentication is the default authentication mode for any site that is hosted on IIS, and it runs under the "IUSR_[ServerName]" account.

What is web garden ?

By default Each Application Pool runs with a Single Worker Process (W3Wp.exe). We can assign multiple Worker Process With a Single Application Pool. An Application Poll with multiple Worker process called Web Gardens. Each Worker Process Should have there own Thread and Own Memory space.

Generally its not recommended to use InProc Session mode while we are using Web Garden.

Where session data stores in case of "In-Proc" Session mode ?

Session data store inside process memory of worker process [ w3wp.exe ] .

How we can create an web garden ?

For creating web graden we need to go to Application Pool, then Right Click on Application Pool > Properties > Goto Performance Tab

In Web Garden Section, increase the number of worker process. By default it is 1.

How we can debug a web application which is hosted on IIS ?

We can easily debug any web application that are hosted on IIS by using Attaching of Worker Process.
From Visual Studio IDE > Tools > Attach To Process
Select the particular Process, then start debugging.

How we can open IIS Configuration manager ?

Just simply Run >inetmgr
Or we can open it from control panel > Administrative tools.

How we can create a Virtual Directory on IIS ?

Open IIS Configuration Manager
First of all Right Click on Default web sites > New > Virtual Directory .
Browse the Physical Path. Set the properites. Click on OK

What are the permission settings are available for Virtual Directory ?

Below are the list of permission that can be set during virtaul directory creation
1. Read
2. Run Scripts
3. Execute:
4. Write:
5. Browse

What is the folder location for Virtual Directory ?

<Drive>:\inetpub\wwwroot

What is the use of Enable Pinging Properties for Application Pool ?

IIS should periodically monitor the health of a worker process [ Idle or not , Time for recycle or not, All Worker process are running properly or not ] .
Pining means, Activation Process monitor Worker process performance, health, idle time etc.
By default it sets to 30s .

Does One Web Application can have multiple Application Pool ?

No. Every Web Application should have one Application Pool. Bydefault it is "DefaultAppPool ".

Which version of IIS is available in Windows Server 2008 ?

IIS 7.0 .
Even Vista Home Premium and Ultimate edition is also having IIS 7.0

How we can save an Application Pool Settings?

Application Pool Settings can be save as "XML" Format.
Right Click on Application Pool > All Task > Save Configuration to a File .
This will save all the settings of Application Pool as an XML file.We can make it password protected also.

Which Tool is used for Remote IIS Debugging ?

Tools is : msvsmon.exe

This is located at : Install path\Microsoft Visual Studio 8\Common7\IDE\Remote Debugger\x86

What are the different authentication mode available for IIS Remote Debugging ?

For IIS Remote Debugging msvsmon supported two authentication mode
1. Windows Authentication
2. No-Authentication

How can we get the list of worker process running in IIS along with the Application pool name

By running iisapp.vbs script from command Prompt.
Below are the steps :
1. Start > Run > Cmd
2. Go To Windows > System32
3. Run cscript iisapp.vbs

If there are multiple worker process running on IIS, then how can you attach a particular worker process for application ?

Well, If there are multiple worker process running in IIS, it means I have to know the name of my application pool. Then I can run cscript iisapi.vbs script to find out the process ID and Application Pool name . Based on the process Id for particular application I have to attache the process from Visual studio IDE.

Why do we need to IIS Remote Debugging ?

There are following reasons where we can use remote debugging
1. Your development server does not have IIS installed.
2. Development server and Build/Released/Hosting Server is different
3. Multiple user want to debug simultaneously.

Does IIS allows multiple user to Remote debug simultaneously ?

Yes. This is one of the great features of msvsmon.exe . Each instance of the remote debugger has a unique server name.we can give an instance of the remote debugger any server name. Now multiple user can able to access the server instance.

What is the use of aspnet_regiis -i command ?

This is used automatically register the .NET Framework with your IIS.

Can we have multiple web sites on IIS ?

Yes. IIS Can have multiple web sites and Each and every web sites can have multiple virtual Directory.

Note : Here web sites means the Root Node.

Where is the default location for IIS Log files ?

C:\WINDOWS\system32\LogFiles\W3SVC1

What is ISAPI Filter ?

This is one of the more important question for experienced guys.
Please read this in details.
http://msdn.microsoft.com/en-us/library/ms524610.aspx

What are the major innovation in IIS 7.0 ?

Below are the Major Innovation in IIS 7.0
Components are designed as module and there are major change in administration settings.
FYI : You can find out many of them, just go thorugh Microsoft IIS web site.

What is the Role of Windows Activation Process in IIS ?

WAP is the Controller of Worker process under a Application Pool. Windows Activation Process which is managed by the worker process by starting, stopping and recycling the application pool. When to start, stop and Recycle should be defined on Application Pool Settings. Activation Process is also responsible for Health Monitor of Application Pool during runtime.

FYI : Health monitoring setting can be easily found in Properties of Application Pool.

What are the different type of application pool available in IIS 7.0 ?

IIS 7.0 having two types of application pool.
1. DefaultAppPool (Integrated)
2. ClassicAppPool

Which is not an Identity of Application Pool ?

NOTE: This is objective type question, Please click question title for correct answer.

Which application pool having maximum privilege on the server ?

NOTE: This is objective type question, Please click question title for correct answer.

What is name of default application pool in IIS ?

NOTE: This is objective type question, Please click question title for correct answer.

What are the worker process for IIS 5.1 and IIS 6.0 ?

For IIS 5.1 > aspnet_wp.exe
For IIS 6.0 > w3wp.exe

Name of the tool which is used for remote debugging of IIS

NOTE: This is objective type question, Please click question title for correct answer.

What is Web Farm ?

This is one of the most question in IIS. And along with that interviewer can as what is the different between Web farm and Web Garden ?

When we hosted our web Application on multiple web server under a load balancer call the Web Farm. This is generally used for heavy load web application where there are many user request at a time. So When Web Application is hosted on Different IIS Server over a load balancer, Load balancer is responsible for distribute the load on different server.

Please have a look into this :
http://www.dotnetfunda.com/articles/article713-difference-between-web-farm-and-web-garden.aspx

What is the default Identity of an Application Pool ?

NetworkServices

How can we set the default page for any web application ?

We can set the default page for a web site from the Virtual Directory Setting.
How To :
IIS Manager > Virtual Directory > Right Click > Properties > GoTo Document Tab.

How we can set the Idle Time out of an worker process ?

We can set the Idle time out for an worker process from Application Pool Properties.
In Performance Tab of Application pool, we can set the Idle Time out of the worker process. This means worker process will shut down after that given time period if it stay idle. And will again wake up again if a new request comes.

Is there any alternative way to host site on IIS rather than opening IIS Manager ?

Yes, We can directly host any site from the physical location of directory itself.
Right Click on Physical Folder > Properties > Web Sharing
There you need to select > "Share This Folder" Option Button. Then it will ask for alias name and other setting. Then Click on OK.
To Validate : Run > Inetmgr > Check there should an virtual directory with the same "Alias" name that you have given.
If there are already one Virtual directory exist it will showing you the error message while you providing the "Alias" name.

Can we create one Application Pool From Another Application Pool ?

Yes. We can.
While creating Application Application Pool From IIS, there should have two option available first one is for Default Setting and Another is for Existing Setting as template.
We can select the second one and from the drop down listed below we can select any on the Application Pool as Template,.

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.

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

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.

For more Information : http://www.codeproject.com/KB/aspnet/aspnetrequestarchitecture.aspx

From where we can set the Session Time Out in IIS ?

We can set the Session time out settings from the Virtual Directory for that site.
Right Click on Virtual Directory > Properties > Click on "Configuration" Button
Goto the "Option" Tab. There in Enable Session State Section you can configure the Session Timeout .

What are the different "Execution Permission" available for IIS for an virtual directory ?
There are three Execution Permission available.
1. None
2. Scripts Only
3. Scripts and Executable

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.

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 "

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.

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.

List of Error & Status codes in IIS 6.0?

Status Code Type of Code
100 Series - Informational
200 Series - Success
300 Series - Redirection
400 Series - Client Error
500 Series - Server Error

How to recycle application pool from the command prompt in IIS7?

1. Use appcmd.exe to recycle the application pool from the command prompt.
2. appcmd.exe is the command line tool for IIS7, you will find this tool at following location :
    %systemroot%\system32\inetsrv\appcmd
3. To recycle your application pool use the following command:
appcmd recycle apppool /apppool.name:<application pool name>

What are the Different steps to be followed to get SSL(Secure Sockets Layer) for our Web Application ?

. Intially we have to Generate a certificate request from our IIS
. Now we have to request a certificate from the certificate authority(CA)
. This CA is an entity which issues Digital Certificates.
. After receiving the certificate we have to install that particular certificate on our Web Server using IIS
. We have to use Secure Hyper Text Transfer Protocol(HTTPS) when accessing secure pages in our application.
By this way we could make our web page as SSL protected. !!!

Which DLL is used to translate XML to SQL in Internet Information Services (IIS) ?

NOTE: This is objective type question, Please click question title for correct answer.

What is the purpose of IIS application pools?
We use applicaiton pools for isolation purpose. Every application within an application pool used the same worker process. Each worker process operates as a separate instance of the worker process executable, W3wp.exe, the worker process that services one application pool is separated from the worker process that services another.

In simplest words we use applicaiton pools for ISOLATION purpose.

what is Windows Process Activation Service ?
The Windows Process Activation Service (WAS) provides process activation, resource management and health management services for message-activated applications. It manages application pool configuration and the creation and lifetime of worker processes for HTTP and other protocols (net.tcp,net.pipe,net.msmq)

Details : http://techprudent.com/the-windows-process-activation-service/
and
MSDN : http://technet.microsoft.com/en-us/library/cc735229%28WS.10%29.aspx

What are the Different Authentication Methods(Using Windows Authentication) which are provided by IIS ?
Generally IIS provides four different kinds of Authentication Methods they are :

Anonymous Method
If we select this authentication, IIS doesn't perform any authentication so that any one can access the application.

Basic Method
If we select this method, the user who access the application should provide windows username and password to access the application. Although this is sent through a network by transmitting direct text so it it very insecure.

Digest Method
This method is almost equal to Basic method but the difference is the password is hashed before it is transmitted through out a network.
Windows Integrated Method
In this the application uses the Kerberos protocol to validate(Authenticate) the user. This uses a Secret key cryptography which provides strign authentication for Client/Server applications.

How can we check whether IIS is being installed in my system or not?
To verify if IIS is installed or not we need to go to ’Add or Remove Programs’ utility in the Control panel and click on the ’Add/Remove Windows Components’ in the side menu.
There we must locate an item called "Internet Information Services (IIS)". If this is checked, IIS should be installed.
So that you can have your IIS installed in your system if it is not installed.

Thanks

R.karthikeyan