Carl Stalhood

Wednesday 10 July 2013

Citrix Interview Questions

1) Explain Citrix Logon Process.

2) Purpose of Zone

Zone is subset of Farm. It is a grouping of Citrix Servers that shares the common Data Collector

3) When would you suggest creating new zones?

Users need to access the closest application in a geographically dispersed environment
Presentation Server is part of a disaster plan that fails over to an alternate location
The same published applications are hosted in multiple zones
User-specific backend data is located in other locations than the main data center
4) 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).

5) When would you suggest creating new farm?

When you want the member servers talk to different datastore – like a test environment;

6) What is a Data Store?
This is the place where all the static information are stored. Farm configuration information, Published Application configurations, Server configurations, Static policy configuration, XenApp administrator accounts, and Printer configurations) that all servers can refer.

7) How to migrate datastore database from SQL2000 to SQL2005 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

8) How to find out the datastore database server name?

Examine the DSN file which contains the connection details to the database.
C:\Program Files\Citrix\Independent Management Architecture\MF20.dsn
The following is an example of an MF20.dsn file from a server connecting to a remote SQL Server instance:
[ODBC]
DRIVER=SQL Server
UID=useraccount
Address=SqlServer,1433
Network=
DATABASE=farmdb
WSID=
APP=Citrix IMA
SERVER=SqlServer

9) 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 MetaFrame server is communicating with the data store.

10) How often does the member servers check datastore database?

By default, every 30 minutes.

11) what happens if datastore connectivity is lost?

If the server loses its connection to the central data store, there’s no limit to how long it will continue to function. (In MetaFrame XP, this is limited to 48 or 96 hours, but that was because the data store also store license information.) But today, the server can run forever from the LHC and won’t even skip a beat if the central connection is lost. In fact now you can even reboot the server when the central data store is down, and the IMA service will start from the LHC with out any problem. (Older versions of MetaFrame required a registry modification to start the IMA service from the LHC.)

12) How will you remove Citrix server from the farm?
If the server is unresponsive, remove it by right click on server in the console.
For functional server, remove it from add/remove programs
use CHFARM command

13) How will you remove citrix server from the datastore DB?
When citrix is uninstalled from the server, it cleans the entry from data store database. Additionally you can run this command to remove the entry from Datastore DB.
DSCHECK /servername

14) How to clean up datastore database?
DSCHEK without parameters will check for consistency and clean up the database. /clean parameter can be used to clean up specific server/application from the datastore but use with caution.

15) How do you troubleshoot printing issues?
Check print spooler service
Check printer mapping errors in event log
Check printer driver availability n compatibility
Check printer policies for over rides

16) How do you configure session printers?
Through Citrix policies. Add the printer drivers first, map the printer and then assign to user/group

17) What does secure gateway d0?

18) What are monitors in Netscaler?
Netscaler uses monitors to track the status of back end servers. These monitors can be http, tcp, ping etc

19) What would you do if you see a service down in Netscaler?
Try pinging the actual server from netscaler CLI and verify its responding

20) How do you configure NetScaler? What are the pre-requisites?

16) Can you monitor Citrix services through EdgeSight?

17) How do you configure alerts in EdgeSight?

18) How many users can you host on XenApp 6.5 vs XenApp 5.0?

19) How do you manage capacity planning with EdgeSight?

20) What are the challenges that you have faced in current environment?

21) What happens if you stop the XML service on a server?

Existing users wont be impacted, but no new users will be able to access the applications published from the server.

22) XML service down on serverA which has 10 applications; can you access the applications?

Existing users wont be impacted, but no new users will be able to access the applications published from the server.

23) What is Citrix XML service?

The Citrix XML server is a component of Citrix XenApp and XenDesktop that’s used to enumerates available resources and provide secure tickets for users that to use the WebInterface or CloudGateway.

XML service has two functions:

Communicating with the XenApp farm / XenDesktop zones; the XML broker
Generating and validating secure ticket to authorize users, the Secure Ticket Authority (STA)
24) How to change the port used by XML service?

By default XML service uses port 80. But citrix recommends using port 8080 inorder to avoid conflicts with IIS.

To change the port used by XML service:

In XenApp 6 and above – this can be changed via Citrix policies.

In Earlier versions – Use the ctxxmlss command-line utility. This can be done by unloading the Citrix XML Service with /u, changing the port with /r and restarting the XML service.

ctxxmlss /u

ctxxmlss /r8080

An alternative method is by changing the port in the registry (and restart the Citrix XML service after changing).

Key :HKLM\System\CurrentControlSet\Services\CtxHTTP

Value: TCP Port

The value is listed in hex, you need to change the view to decimal.

25) Explain Citrix Load Levels?

The following are explanations of the load levels:
9999 : No load balancing installed
0 to 9998 : “normal” load level
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

26)How to recover Citrix License Server?
The Citrix servers can function without contacting the license server and it is 30-days fault tolerant, and in Enterprise version an alert can be set with Resource Manager to send an email in case of License Server Connection Failure. If the license server reconnects at any time in the thirty days the problem resolves itself. If the server is not going to come back up, then the license file, digitally signed with the case-sensitive hostname of the old license server, is the critical component. The license file, a *.lic file, can be backed up to a thumb drive separately, and restored to a new server with the same name of the old license server, and the Citrix License server software installed.
27)How to recover from IMA failing?
There are many reasons that the IMA Service doesn’t start
1. IMA Service load time
2. IMA Service subsystem
3. Missing Temp directory
4. Print spooler service
5. ODBC configuration
6. Roaming Profile
Check the Windows Registry setting: HKEY_LOCAL_MACHINESOFTWARECitrixIMARuntimeCurrentlyLoadingPlugin
If there is no value specified in the CurrentlyLoadingPlugin portion of the above Windows Registry entry then the IMA Service could not connect to the data store or the local host cache is missing or corrupt.
If a CurrentlyLoadingPlugin value is specified the IMA Service made a connection to the data store and the value displayed is the name of the IMA Service subsystem that failed to load.
If administrators see an “IMA Service Failed” error message with an error code of 2147483649 when starting the Presentation Server the local system account might be missing a Temp directory which is required for the IMA Service to run.
Change the IMA Service startup account to the local administrator and restart the server. If the IMA Service is successful in starting under the local administrator account then it is likely that a missing Temp directory for the local system account is causing the problem.
If the Temp directory is not present then manually create one as >Temp. For example: C:\Windows\Temp
Also verify that the TMP and TEMP system environment variables point to the temporary directory. Restart the server to restart the IMA Service

28) What is new in XenApp 6.5?
Session Lingering
Session Pre-Launch
App Center
Load Evaluators assigned to Worker Groups or OUs instead of individual servers
Datastore and Zone information configured via GPO
Sesssion Only and Controller roles
Desktop Director web console can manage XenApp sessions
MultiStream ICA – ica traffic can be split into four separate TCP streams if required
Log On control feauture to drain users.

29) 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.