Sunday, March 24, 2013

Difference between Shared, VPS, and Dedicated Hosting

Shared Hosting
 Shared Hosting is very similar to living in an Apartment Complex. All residents are in the same location and must share the available resources with everyone - such as the pool, parking lot, and play ground. In shared hosting, all accounts (sites) must share the available resources with all the other accounts on the server - such as CPU time, memory, and disk space.

VPS Hosting
 VPS Hosting is similar to owning a Condo. While you still share things on the property, you are ultimately responsible for maintaining your own property and repairs inside the condo. There is also significantly less residents per building and assigned parking. On a Virtual Private Server, you are allotted resources that are not shared by everyone. The over all CPU time and memory are shared across all accounts on the machine, but at the same time portions of those resources are always dedicated to each account. This allows for more power and flexibility than being on a shared account. 

Dedicated Hosting
 Dedicated Hosting can be compared to owning a house. You are allowed and have access to all resources available on the machine. No one else's account resides on the machine (your house) and would not be capable of tapping into your resources.

Now that you know a little bit more about hosting, which is right for you? A VPS or dedicated server?
  

Comparison between VPS and Dedicated server 

Hardware

VPS

You are still sharing server hardware with other users. However, you server is virtualized which means it runs as though it is on a dedicated server. That means you can restart services, make modifications to server files, and create other user hosting accounts.

Dedicated

You are on your own here. The entire server is yours to play with. That means all the hardware specs (CPU, RAM, data transfer, etc.) are yours. Also, you can have more flexibility with hardware setups. For example, need an extra 500GB of storage? Then this could added by the support team for an additional fee.

Software

VPS

You are free to install whatever program you want. However, if it starts pulling on resources and starts pulling resources from other VPS customers, then this could be an issue and cause your website performance to slow or become suspended for abuse.

Dedicated

Regardless of how your software programs perform, you are free to install any programs you please. A high resource program will not affect others expcept for any clients you are managing.

Budget

VPS

Given the hardware specs and freedom you get on a VPS, the performance boost on a VPS is more budget friendly.

Dedicated

More expensive than VPS hosting because you do get your own server and better specs.

Saturday, March 23, 2013

About Internet Protocol- IPV6 (Part-2)



The Internet Corporation for Assigned Names and Numbers (ICANN) is responsible for the assignment of IPv6 addresses. ICANN assigns a range of IP addresses to Regional Internet Registry (RIR) organizations. The size of address range assigned to the RIR may vary but with a minimum prefix of /12 and belong to the following range: 2000::/12 to 200F:FFFF:FFFF:FFFF::/64.

Each ISP receives a /32 and provides a /48 for each site-> every ISP can provide 2(48-32) = 65,536 site addresses (note: each network organized by a single entity is often called a site).
Each site provides /64 for each LAN -> each site can provide 2(64-48) = 65,536 LAN addresses for use in their private networks.
So each LAN can provide 264 interface addresses for hosts.
-> Global routing information is identified within the first 64-bit prefix.
Note: The number that represents the range of addresses is called a prefix


Now let’s see an example of IPv6 prefix: 2001:0A3C:5437:ABCD::/64:

In this example, the RIR has been assigned a 12-bit prefix. The ISP has been assigned a 32-bit prefix and the site is assigned a 48-bit site ID. The next 16-bit is the subnet field and it can allow 216, or 65536 subnets. This number is redundant for largest corporations on the world!
The 64-bit left (which is not shown the above example) is the Interface ID or host part and it is much more bigger: 64 bits or 264 hosts per subnet! For example, from the prefix 2001:0A3C:5437:ABCD::/64 an administrator can assign an IPv6 address 2001:0A3C:5437:ABCD:218:34EF:AD34:98D to a host.
IPv6 Address Scopes
Address types have well-defined destination scopes:
IPv6 Address Scopes              
Description
Link-local address
+ only used for communications within the local subnetwork (automatic address configuration, neighbor discovery, router discovery, and by many routing protocols). It is only valid on the current subnet.
+ routers do not forward packets with link-local addresses.
+ are allocated with the FE80::/64 prefix -> can be easily recognized by the prefix FE80. Some books indicate the range of link-local address is FE80::/10, meaning the first 10 bits are fixed and link-local address can begin with FE80, FE90,FEA0 and FEB0 but in fact the next 54 bits are all 0s so you will only see the prefix FE80 for link-local address.
+ same as 169.254.x.x in IPv4, it is assigned when a DHCP server is unavailable and no static addresses have been assigned
+ is usually created dynamically using a link-local prefix of FE80::/10 and a 64-bit interface identifier (based on 48-bit MAC address).
Global unicast address
+ unicast packets sent through the public Internet
+ globally unique throughout the Internet
+ starts with a 2000::/3 prefix (this means any address beginning with 2 or 3). But in the future global unicast address might not have this limitation
Site-local address
+ allows devices in the same organization, or site, to exchange data.
+ starts with the prefix FEC0::/10. They are analogous to IPv4′s private address classes.
+ Maybe you will be surprised because Site-local addresses are no longer supported (deprecated) by RFC 3879 so maybe you will not see it in the future.

All nodes must have at least one link-local address, although each interface can have multiple addresses.
However, using them would also mean that NAT would be required and addresses would again not be end-to-end.
Site-local addresses are no longer supported (deprecated) by RFC 3879.
Special IPv6 Addresses
Reserved Multicast Address
Description
FF02::1
+ All nodes on a link (link-local scope).
FF02::2
+ All routers on a link
FF02::5
+ OSPFv3 All SPF routers
FF02::6
+ OSPFv3 All DR routers
FF02::9
+ All routing information protocol (RIP) routers on a link
FF02::A
+ EIGRP routers
FF02::1:FFxx:xxxx
+ All solicited-node multicast addresses used for host auto-configuration and neighbor discovery (similar to ARP in IPv4)
+ The xx:xxxx is the far right 24 bits of the corresponding unicast or anycast address of the node
FF05::101
+ All Network Time Protocol (NTP) servers
Reserved IPv6 Multicast Addresses
Reserved Multicast Address
Description
FF02::1
+ All nodes on a link (link-local scope).
FF02::2
+ All routers on a link
FF02::9
+ All routing information protocol (RIP) routers on a link
FF02::1:FFxx:xxxx
+ All solicited-node multicast addresses used for host auto-configuration and neighbor discovery (similar to ARP in IPv4)
+ The xx:xxxx is the far right 24 bits of the corresponding unicast or anycast address of the node
FF05::101
+ All Network Time Protocol (NTP) servers



Thanks
R.karthikeyan

Monday, March 18, 2013

About Internet Protocol- IPV6

Internet has been growing extremely fast so the IPv4 addresses are quickly approaching complete depletion. Although many organizations already use Network Address Translators (NATs) to map multiple private address spaces to a single public IP address but they have to face with other problems from NAT (the use of the same private address, security…). Moreover, many other devices than PC & laptop are requiring an IP address to go to the Internet. To solve these problems in long-term, a new version of the IP protocol – version 6 (IPv6) was created and developed.
IPv6 was created by the Internet Engineering Task Force (IETF), a standards body, as a replacement to IPv4 in 1998. So what happened with IPv5? IP Version 5 was defined for experimental reasons and never was deployed.
While IPv4 uses 32 bits to address the IP (provides approximately 232 = 4,294,967,296 unique addresses – but in fact about 3.7 billion addresses are assignable because the IPv4 addressing system separates the addresses into classes and reserves addresses for multicasting, testing, and other specific uses), IPv6 uses up to 128 bits which provides 2128 addresses or approximately 3.4 * 1038 addresses. Well, maybe we should say it is extremely extremely extremely huge :)

IPv6 Address Types
Address Type Description
Unicast One to One (Global, Link local, Site local)
+ An address destined for a single interface.
Multicast One to Many
+ An address for a set of interfaces
+ Delivered to a group of interfaces identified by that address.
+ Replaces IPv4 “broadcast”
Anycast One to Nearest (Allocated from Unicast)
+ Delivered to the closest interface as determined by the IGP
A single interface may be assigned multiple IPv6 addresses of any type (unicast, anycast, multicast)
IPv6 address format
Format:
x:x:x:x:x:x:x:x – where x is a 16 bits hexadecimal field and x represents four hexadecimal digits.
An example of IPv6:
2001:0000:5723:0000:0000:D14E:DBCA:0764

There are:
+ 8 groups of 4 hexadecimal digits.
+ Each group represents 16 bits (4 hexa digits * 4 bit)
+ Separator is “:”
+ Hex digits are not case sensitive, so “DBCA” is same as “dbca” or “DBca”…
IPv6 (128-bit) address contains two parts:
+ The first 64-bits is known as the prefix. The prefix includes the network and subnet address. Because addresses are allocated based on physical location, the prefix also includes global routing information. The 64-bit prefix is often referred to as the global routing prefix.
+ The last 64-bits is the interface ID. This is the unique address assigned to an interface.
Note: Addresses are assigned to interfaces (network connections), not to the host. Each interface can have more than one IPv6 address.
Rules for abbreviating IPv6 Addresses:
+ Leading zeros in a field are optional
2001:0DA8:E800:0000:0260:3EFF:FE47:0001 can be written as
2001:DA8:E800:0:260:3EFF:FE47:1
+ Successive fields of 0 are represented as ::, but only once in an address:
2001:0DA8:E800:0000:0000:0000:0000:0001 -> 2001:DA8:E800::1
Other examples:
– FF02:0:0:0:0:0:0:1 => FF02::1
– 3FFE:0501:0008:0000:0260:97FF:FE40:EFAB = 3FFE:501:8:0:260:97FF:FE40:EFAB = 3FFE:501:8::260:97FF:FE40:EFAB
– 0:0:0:0:0:0:0:1 => ::1
– 0:0:0:0:0:0:0:0 => ::
IPv6 Addressing In Use
IPv6 uses the “/” notation to denote how many bits in the IPv6 address represent the subnet.
The full syntax of IPv6 is
ipv6-address/prefix-length
where
+ ipv6-address is the 128-bit IPv6 address
+ /prefix-length is a decimal value representing how many of the left most contiguous bits of the address comprise the prefix.
Let’s analyze an example:
2001:C:7:ABCD::1/64 is really
2001:000C:0007:ABCD:0000:0000:0000:0001/64
+ The first 64-bits 2001:000C:0007:ABCD is the address prefix
+ The last 64-bits 0000:0000:0000:0001 is the interface ID
+ /64 is the prefix length (/64 is well-known and also the prefix length in most cases)

Thanks
R.karthikeyan

Saturday, March 16, 2013

Back Up and Restore of System Databases (SQL Server)


SQL Server maintains a set of system-level databases, system databases, which are essential for the operation of a server instance. Several of the system databases must be backed up after every significant update. The system databases that you must always back up include msdb, master, and model. If any database uses replication on the server instance, there is a distribution system database that you must also back up. Backups of these system databases let you restore and recover the SQL Server system in the event of system failure, such as the loss of a hard disk.
The following table summarizes all of the system databases.
System database Description Are backups required? Recovery model Comments
master The database that records all of the system level information for a SQL Server system. Yes Simple Back up master as often as necessary to protect the data sufficiently for your business needs. We recommend a regular backup schedule, which you can supplement with an additional backup after a substantial update.
model The template for all databases that are created on the instance of SQL Server. Yes User configurable1 Back up model only when necessary for your business needs; for example, immediately after customizing its database options.
Best practice:  We recommend that you create only full database backups of model, as required. Because model is small and rarely changes, backing up the log is unnecessary.
msdb The database used by SQL Server Agent for scheduling alerts and jobs, and for recording operators. msdb also contains history tables such as the backup and restore history tables. Yes Simple (default) Back up msdb whenever it is updated.
Resource (RDB) A read-only database that contains copies of all system objects that ship with SQL Server 2005 or later versions. No The Resource database resides in the mssqlsystemresource.mdf file, which contains only code. Therefore, SQL Server cannot back up the Resource database.
Note Note
You can perform a file-based or a disk-based backup on the mssqlsystemresource.mdf file by treating the file as if it were a binary (.exe) file, instead of a database file. But you cannot use SQL Server restore on the backups. Restoring a backup copy of mssqlsystemresource.mdf can only be done manually, and you must be careful not to overwrite the current Resource database with an out-of-date or potentially insecure version.
tempdb A workspace for holding temporary or intermediate result sets. This database is re-created every time an instance of SQL Server is started. When the server instance is shut down, any data in tempdb is deleted permanently. No Simple You cannot back up the tempdb system database.
Configure Distribution A database that exists only if the server is configured as a replication Distributor. This database stores metadata and history data for all types of replication, and transactions for transactional replication. Yes Simple For information about when to back up the distribution database, see Back Up and Restore Replicated Databases.
1 To learn the current recovery model of the model, see View or Change the Recovery Model of a Database (SQL Server) or sys.databases (Transact-SQL).

Limitations on Restoring System Databases

  • System databases can be restored only from backups that are created on the version of SQL Server that the server instance is currently running. For example, to restore a system database on a server instance that is running on SQL Server 2005 SP1, you must use a database backup that was created after the server instance was upgraded to SQL Server 2005 SP1. 
  • To restore any database, the instance of SQL Server must be running. Startup of an instance of SQL Server requires that the master database is accessible and at least partly usable. If master becomes unusable, you can return the database to a usable state in either of the following ways:
    • Restore master from a current database backup.
      If you can start the server instance, you should be able to restore master from a full database backup.
    • Rebuild master completely.
      If severe damage to master prevents you from starting SQL Server, you must rebuild master. For more information, see Rebuild System Databases.
      Important noteImportant
      Rebuilding master rebuilds all of the system databases.


Thanks
R.karthikeyan

Wednesday, March 13, 2013

What is NAT (Network Address Translation)?



Primarily NAT was introduced to the world of IT and networking due to the lack of IP addresses, or looking at it from another view, due to the vast amount of growing IT technology relying on IP addresses. To add to this, NAT adds a layer of security, by hiding computers, servers and other IT equipment from the outside world.

How NAT works
When computers and servers within a network communicate, they need to be identified to each other by a unique address, in which resulted in the creation of a 32 bit number, and the combinations of these 32 bits would accommodate for over 4 billion unique addresses, known as IP address. This was named IPv4, and although over 4 billion addresses sounds a lot, it really is not considering how fast the world of computers and the internet has grown.
To circumvent this problem, a temporary solution was produced known as NAT. NAT resulted in two types of IP addresses, public and private. A range of private addresses were introduced, which anyone could use, as long as these were kept private within the network and not routed on the internet. The range of private addresses known as RFC 1918 are;

Class A 10.0.0.0 - 10.255.255.255

Class B 172.16.0.0 - 172.31.255.255

Class C 192.168.0.0 - 192.168.255.255

NAT allows you to use these private IP address on the internal network. So within your private network you would assign a unique IP address to all your computers, servers and other IP driven resources, usually done via DHCP. Another company can use the same private IP addresses as well, as long as they are kept internal to their network. So two companies maybe using the same range of IP addresses but because they are private to their network, they are not conflicting with each other.
However when internal hosts do need to communicate to the public network (Internet) then this is where a public address comes into the equation. This address usually purchased from an ISP is a routable public address everyone can see, which would represent your network gateway. This public address would be unique, no one else would use this address.

Now getting to the point; When a host on the internal network with an internal IP address does need to communicate outside it's private network, it would use the public IP address on the network's gateway to identify itself to the rest of the world, and this translation of converting a private IP address to public is done by NAT. For example a computer on an internal address of 192.168.1.10 wanted to communicate with a web server somewhere on the internet, NAT would translate the address 192.168.1.10 to the company's public address, lets call this 1.1.1.1 for example. so that the internal address is identified as the public address when communicating with the outside world. This has to be done because when the web server somewhere on the internet was to reply to this internal computer, it needs to send this to a unique and routable address on the internet, the public address. It can not use the original address of 192.168.1.10, as this is private, none routable and hidden from the outside world. This address, of 1.1.1.1 would be the address of the public address for that company and can be seen by everyone. Now the web server would reply to that public address, 1.1.1.1. NAT would then use its records to translate the packets received from the web server that was destined to 1.1.1.1 back to the internal network address of 192.168.1.10, and though the computer who requested the original info, will receive the requested packets.

Now you can obviously see the two benefits of NAT. Firstly it would save on the IP addresses we use, as every single computer does not need a public address, and also it would hide these private computers from the outside world. Everyone can only see the public address, the rest is hidden behind this public address. So from the internet only the public address on the external interface of the firewall or router can be seen, and nothing beyond it.

Types of NAT
Three main types of NAT rules are used today depending on what needs to be accomplished;

Static NAT
A pool of public IP addresses are assigned to the NAT device. A private IP address can then be statically mapped to anyone of these public addresses. This type of NATTING scheme is usually used for servers requiring the same IP address always, hence the name "static", so server 1 will always have the same IP address assigned to it, server 2 will have a different public IP address assigned to it and so on.

Dynamic NAT
Again the NAT device will consist of a pool of IP addresses. This time though the pool of IP addresses will be used when needed and then given back to the pool. So if computer A needed a public address, it would take one from the pool, then hand it back when done. The next time the same computer wanted an IP address it may be assigned a different public address from the pool, because the one used previously may be in use by another computer, hence the name "dynamic". So users who want to communicate on the internet at any one time will be limited by how many public IP addresses are available in the NAT pool. A company would purchase a number of public IP's depending on their need.

Port Address Translation (PAT)
In this type of setup, a company would only have one public IP address assigned to their network, and so everyone would share this one public address when using the internet, browsing the web for example. Yes, you may be asking how can everyone share one address, well the clue lies within the name, Port address translation. When a computer wants to use the internet, the NAT device, using the PAT method will remember the IP address and source port of the internal host. For example 192.168.1.10 with a source port of 55331 wanted to browse Amazon.com. The NAT device will keep a note of this, and when Amazon replies to the public address and the port number of 55331, the NAT device will use the PAT method and look up the port information which maps to the internal computer requesting it. So it would be saying, this information Amazon has sent back to the public address and port number 55331, maps to the IP address 192.168.1.10 who originally requested it, though the information is for that computer. So the connections are uniquely identified by a source port, all using the same public IP but with unique source ports to identify who requested what information.
A company would save a reasonable amount of money and IP addresses using this method because it is only using one IP address. This has been a major factor to why IPv6 has been mentioned for some years now but still not required in most countries.

NAT is also implemented in home based routers and hardware firewalls such as the Netgear's and the Linksys of this world as well as the high end hardware firewalls such as the likes of Cisco and Juniper.
This has proved a valuable feature on hardware firewalls for saving public IP addresses and also a countermeasure for some types of attacks such as a reconnaissance attack.

Disadvantages of NAT
As with everything, NAT does have it's drawbacks. Some applications and services such as VPN and video conferencing struggle to process via NAT (Not entirely true as you can most of the time get them configured to work with NAT, but can get a little messy when setting rules up in applications,, routers and firewalls).

IPv6
However to circumvent the above issue a few extra public IP addresses can be purchased for these dedicated services. For the long run however, IPv6 is already being rolled out in some technologies and some parts of the world. This addressing scheme uses 128bit numbering scheme as opposed to IPv4's 32bits used for addresses. IPv6 supports 2 to the power of 128 addresses, compared to IPv4's 2 to the power of 32, now that is a massively huge increase of IP addresses, though future proofing the growth of IP addressing using IPv6.

Thanks
R.karthikeyan

How to add a Second Domain Controller in Windows 2008 domain


Domain controller as server for hosting your company Active Directory (AD) is very important part of your network infrastructure. In case of its failure logging users on AD is impossible. Because of that one of the main things in planning your network infrastructure is make plan for implementing redundant domain controller in network infrastructure. In case you have it, failure of one of them does not mean that user will be unable to log on the system. Since failed domain controller is up again, backup controller will be in function of users authentication or other functions which it can have (DNS server etc.). On this way your network can stay functional, reliable and more resistible to failures.
In this article I will describe process of adding additional domain controller in your Windows network infrastructure.
First step is start dcpromo program to create new domain controller. Go to Start and type dcpromo in run field:
Click on OK. Opens first window in process of new DC creating:
When you want to add new DC Use advanced mode installation option should be unchecked because it use for Read Only Domain controller creating. In this case we want new DC with all functionalists as primary DC and read only mode is not option in that case. Click on Next.
In this window some information about operating system compatibility are displayed. Click on Next to continue.
Next window offers choosing option for add new or additional domain controller:
There are two options: to create new forest or to add DC in existing forest. If we have to add additional DC which is option described in this article Existing forest option should be checked. When this option is checked you have possibility to add new domain controller in existing domain or create new domain in existing forest. Here we want to add new DC in existing domain which will backup DC for our primary DC which exists in network. Because of that Add a domain controller to existing domain should be checked. When appropriate option are checked click on Next.
In next window domain name and network credentials for adding new DC should be set:
First, type the name of domain for which you want to add additional DC (testdomain.com in this example). After that credentials for adding DC should be chased. Main thing is that the credentials with which you adding DC should have administrative privileges. In this case we will use credentials of user from domain administrators group.
In network credentials type username and password of user which you use for promoting new DC. Then click OK.
In next step you should choose domain for which your server will be domain controller. By default, your domain will be set:
Chose default option and click Next. Opens window for site selecting.
Leave default option and click Next.
Next window is window for additional domain controller options. These are Global catalog, DNS server and Read Only Domain Controller. For additional DC you should chose DNS server and Global catalog options as it is shown on next picture:
Check DNS server and Global catalog options and click Next. Opens windows for choosing locations for database, SYSVOL and NTDS files. It is recommended to leave default options for these parameters.
Click Next. Opens window for setting restore mode password:
Restore mode account in Active Directory is different then domain administrator account. If you start domain controller in restore mode this account is used. So type password for restore mode account and click Next. Appears window with summary information about options you chose during installation additional domain controller:
When installation process is finished appears last window on which you simple should click on Finish button to finish installation process:
Now you will be prompted for restart computer and then you can log in to your new domain controller computer.
In this article I described how to set additional domain controller in our network. On this way you will make your network more reliable and stable.


Thanks
R.karthikeyan

Tuesday, March 12, 2013

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

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