Citrix XenApp Components Interview Questions

Below are some commonly asked Interview Questions on Citrix XenApp Components. Our previous blog contains questions on Citrix XenApp Installation and upcoming blog will cover Troubleshooting scenarios.

What is a Citrix Xenapp farm?

Farm is group of XenApp servers where we are going to publish the applications

What is a Data collector?

Stores dynamic information, for each of the Zones in a farm we will have a data collector. Ex: how many users are on a server, what the users are doing, what applications are being run.

What is a Citrix XenApp Data store?

It Stores static information, farm has a single data store, and data store is connected by some data connection, like SQL or Oracle.

How many data collectors will have in the 30 XenApp server farm?

It depends on zones, by default we have 1 data collector but for load balancing we are going to configure at least 2-3.

How you are describing zones? Or what’s the purpose of zones?

Zones are creating for to identify xenapp servers as geographical locations. For example we have 10 xenapp servers in India, 30 in US and 10 in Australia then we are going to configure zones.

So, for example 10 XenApp servers in india, how many data collectors you had it in this scenario and which is going to acts as a data collector?

By default first XenApp server is data collector. We have 2 data collector in this environment.

How you are going to check which server is the data collector?

Qfarm is the command to check which server is act as zone data collector.

How big a zone can get?

It’s just a matter of looking at the traffic patterns. For instance, do you want one single data collector updating 1000 servers whenever you make a change to the environment (one zone), or do you want two data collectors to each update only 500 servers (one zone).

What is the main purpose of the Data Collector?

The zone data collector is simply a xenapp Server which is performing the data collector role in a particular zone. The xenapp server maintaining the data collector roll is responsible for directing all requests from Users (ICA clients or receivers) launching published applications

When would you suggest creating new zones?

• Users need to access the closest application in a geographically dispersed environment
• XenApp Server is part of a disaster plan that fails over to an alternate location
• The same published applications are hosted in multiple geographical locations
• User-specific backend data is located in other locations than the main data center

When would you suggest creating new farm?

When you want the member servers talk to different data store – like a test environment or if it’s different xenapp versions;

What is ICA?

ICA is Independent Computing Architecture for accessing the applications from xenapp servers. It was created by CITRIX and its work with 10kbps. Citrix actually replaced the terminal servers RDP with its own protocol called ICA. ICA protocol is not transferring the real data back and forth, its just updating screen updates and mouse clicks from server to client and client to server. With ica protocol the users can print to their local printers.

What is an .ICA File, What is contained inside an ica File?

Independent Computing Architecture (ICA) file used by Citrix application servers; contains configuration information for connecting to different servers.

Differences between ICA and RDP?

• RDP works only under TCP/IP, while ICA works on many protocols.
• RDP doesn’t permit applications to run in a browser, while works for ICA
• Encryption is possible in ICA, it is not present in RDP\
• ICA- Independent Computing Architecture (Citrix Protocol) 1494, RDP- Remort Desktop Protocol (Microsoft protocol) 3389
• ICA also supports non windows like Linux, UNIX, Apple Mac OS and soft mobiles
• RDP supprots only desktop or server console.
• ICA supprots published applicaion, Desktop, Content, and it will work under 10kb- 20kb
• Session Reliability will be there in ICA,it is not in the RDP

What is IMA?

IMA is the independent management architecture and once you configured xenapp server, its available on every xenapp server to communicate between servers to server. IMA is always depends on datastores.

What would happen if you stop the IMA service on a server?

Existing users on the server will not face any issues, but no new user connections to the server would be allowed.

How often does the member servers check datastore database?

By default it will check every 30 minutes.

What is the function of local host cache in citrix?

Local host cache is available on each xenapp server. Its like a mini data base, for example if a XENAPP server losses its connectivity to data store then it will use the information it has in its local host cache.

How to verify Datastore DB connectivity?

To determine if a server is communicating regularly with the data store, check the following registry key:

HKEY_LOCAL_MACHINE\SOFTWARE\CITRIX\IMA\DataStoreFailureTime

If the value is all zeros, the server is communicating with the data store.

How to migrate datastore database from SQL2005 to SQL2008R2 OR How to recover datastore database?
Restore the DB to new server
Change mf20.dsn on all servers starting with data collectors
Restart IMA service on all servers

What are the different ports uses in Citrix?

80: This is the default port used by the XML service and is used by clients who enumerate applications with the TCP+HTTP or XML protocol. You will thus need to open this port on your firewall for inbound connections if clients will be using it to locate servers. You can change the port easily enough using the CTXXMLSS command.

443: This is the default SSL. The SSL Relay will use it to secure communications between the Web Interface and the server farm. You could also use it to secure client communication to the web Interface or use it for client connections to the Presentation Server.

1433: The port used to communicate with a Microsoft SQL data store.

1494: Any client using the TCP protocol to communicate with the xenapp Server uses this port. You will need to open this port on your firewall for inbound connections unless you are using some form of encapsulation or encryption.

1521: This port is used to communicate with the Oracle data store.

2512: This port is used for server-to-server communication such as when load information is communicated. The port used to access the data store is saved in the HKLMSOFTWARECITRIXIMAIMAPORT key on the server containing the data store. All other servers use the port number saved in HKLMSOFTWARECITRIXIMAPSSERVERPORT key in the registry to access the data store. Have a look at IMAPORT to see how to change it.

2513: This port is used by the xenapp Server Console when connection to a server. Have a look at IMAPORT to see how to change it.

2598: This is the session reliability port number and needs to be opened on your firewall if the ICA Clients will be using session reliability when communication with the server.

27000 and a random port number: This is the port used for communication between the Citrix License server and the xenapp Servers. Remember that the Citrix vendor daemon running on the license server uses a random port. It tracks license usage.

What are the query commands in Citrix?

• qfarm
• querydc
• queryds
• queryhr

What is the Citrix XML Service?

Citrix XML Service (CtxHttp) is installed as a service.

For application discovery and configuration information, XML service should be up and running

What is printer terminology in citrix?

Citrix Printing can be configured 3 ways (types)

• Client Printing: The printer connected to the Workstation & the drivers are installed on the Citrix server for printing.
• Network Printing: The Printer connected to the print server & the drivers should be available
• on the Citrix server.
• Local Printing: The printer connected to locally to the Citrix server & the driers are installed for the print operation.

What are different load evaluators are available in Citrix?

• Default Load Evaluators
• Advance Load evaluators
• Custom load evaluators

Take a scenario, A farm contains 10 servers. An application is published on two of the servers. We have to make sure when the number of users connecting to the application exceeds 100 it needs to show full load. Which load evaluator you are going to configure in this scenario?

We have to configure Custom load evaluator assigned to the server

Which role is assigned to a custom XenApp Administrator by default?

Log on to Management Console

Explain Citrix Load Levels?

The following are explanations of the load levels:

 

0 to 9998             :    “normal” load level

9999                         :     No load balancing installed
10000!             :     Application is disabled for this server
10000                         :     Load is at 100%
10001                         :     Out of licenses
10002                         :    Indicates that no ICA connections, listener is disabled, are available on that server.
20000                        :     Citrix server is unable to reach license server