Essential Ubuntu Cloud Interview Questions & Answers:

1. Do you know how does networking play an important role in security?

To prevent eavesdropping of network traffic from a machine run by one user to the machines run by other users, networking plays an important role in security. Following networking modes are available at set-up time, depending on the level of security:
SYSTEM Mode
STATIC Mode
MANAGED Mode
MANAGED-NOVLAN Mode

2. Explain what was the requirement of the initial addition of node controller?

The initial addition of Node Controller required a password to exchange the cryptographic keys from the lower controller to the upper one. After the password is exchanged, all operations rely on the trust provided by these keys in the communications between the controllers.

3. Tell me what are the tasks performed by Node controller?

Node controller consists of the hardware settings and configuration for the image machines. It performs the tasks that are requested by cluster controller and reply to the queries. It performs the following tasks:
1. Verify and authenticate the user request.
2. Allow user to download the image from the cache and use it.
3. Create a virtual network interface for easy communication between machines.
4. Start an instance of a virtual machine that can be accessed by the user.

4. Explain what is the function of Walrus storage controller?

Walrus storage controller uses SOAP API that are compatible with its architecture. Its main function is:
? To store the machine images that can be used by the cloud controller
? To access and store the data from anywhere.
? It provides file level storage system and doesn't provide the locking of a file. It doesn't allow concurrent file to change the status of a single file that is getting modified by the user.
? It saves the state of the images.

5. Tell me how IP addressing is managed in Ubuntu cloud?

The IP addressing is an essential part of networking and to establish an ubuntu cloud it has to be configured correctly and the default gateway has to be mentioned for communication with other network or same network. To configure the IP addressing the command that can be used is ip, ifconfig and route. These are the commands that allow the configuration of the networking. To set the configuration use the following command:
sudo ifconfig eth0 10.0.0.100 netmask 255.255.255.0
Through this IP address can be set and configured temporarily to save it permanently ifconfig file has to be modified.

6. Explain what are the limitations/demerits of Ubuntu cloud?

Cloud computing ahs a few disadvantages, some of them are:

Security and privacy: The data in Ubuntu cloud have many instances with a third party which many users may not prefer. Cloud servers store sensitive information which must be protected at all costs. There is a vulnerability of unauthorized access.
Loss of control (dependency): In cloud computing the cloud service providers play a major role more maintenance and fixing of the cloud. Being a third party an organization has less control over it. And once a cloud is established migrating to another CSP is not an easy task.
Costs: Although in the long run cloud computing is cheap but being a new technology the improvements and research involved makes it quite expensive. To incorporate this technology many changes may be require including the development of software.
Integration and knowledge: As most of the functions are provided by a CSP getting to understand the system from an organizational point of view is tough. Also integration with existing systems is hard to achieve.

7. Tell me how to identify Ethernet interfaces in Ubuntu cloud?

Ethernet interfaces are the part of the networking and it is automatically identified by the system using different naming conventions. It is represented by ethX, where X= any numeric value. The default interface of the system is named as eth0 and it will go on after this. To identify the Ethernet interface the command that is used:
ifconfig -a | grep eth
eth0
Link encap:Ethernet
HWaddr 00:15:c5:4a:16:5a

The command will show all the interfaces that are associated with the system.

8. Explain what are elements included in Ubuntu cloud architecture?

The elements that are included in ubuntu cloud architecture are:
1. Cloud controller: it is the main controller that controls the communication between two nodes and allows the system to communicate with each other.
2. Walrus Storage controller: It controls the storage of the data and resource at one place for easy access.
3. Elastic block storage controller: it uses the elasticity concept and allow the resources to scale up as the demand rises. This block consists of dynamic resources.
4. Cluster controller: it controls the cloud clusters which are made up of mady nodes and contains the configuration of all the nodes from a single point.
5. Node controller: it consists of the hardware resources that is being provided to the web or to the user through cluster controller.

9. Tell me what does private cloud offer in building an infrastructure?

Private cloud offers complete set of development tools and easy to configure panel where you can customize and deploy prototype applications.
- It keeps the private sensitive application separate and hidden from the world.
- It provides the provision to create high performance applications and include the concept of elasticity.
- It uses a firewall and keeps all the resources in a pool that separates them with other resources that are made public.

10. Explain a few of the uses of the private cloud concept?

The private cloud concept has a variety of usage scenarios. Some of them are :

- It enables an organization to rapidly develop and also prototype cloudware applications. Also this can be done behind a firewall enabling the creation/development of privacy sensitive applications such as classified data handling.
- Being an elastic platform it enables the use of high performance applications whose load can be fluctuating. The system is based on aggregated peak loads of different applications at a single point of time.
- By using private cloud concept the organization can assign a pool of hardware inside the firewall henceforth enabling it to be assigned to the users by a common gui to speed up the process.