The differences in responsibilities are listed below:

- QA is concern for Process Quality and Programmers are concern for Product Quality.

- QA ensure that the processes used for developing the product of high quality where as programmers used these processes so that end product is of good quality.

- Processes are decided by QA. Programmers are supposed to follow the processes so that they can produce a good quality product.

- Any issue found during execution of process by the programmers is communicated to the QA so that they can improve the process.

Quality Assurance (QA): QA refers to the planned and systematic way of monitoring the quality of process which is followed to produce a quality product. QA tracks the outcomes and adjusts the process to meet the expectation.

Quality Control (QC): Concern with the quality of the product. QC finds the defects and suggests improvements. The process set by QA is implemented by QC. The QC is the responsibility of the tester.

Software Testing: is the process of ensuring that product which is developed by the developer meets the user requirement. The motive to perform testing is to find the bugs and make sure that they get fixed.

With static IP addressing, a computer (or other device) is configured to always use the same IP address. With dynamic addressing, the IP address can change periodically and is managed by a centralized network service

The address resolution protocol(ARP) is used to associate the 32 bit IP address with the 48 bit physical address, used by a host or a router to find the physical address of another host on its network by sending a ARP query packet that includes the IP address of the receiver.

The reverse address resolution protocol (RARP) allows a host to discover its Internet address when it knows only its physical address.

TCP-Transmission Control Protocol

UDP- user Datagram protocol

UDP is user assisted program and converts the application into the encapsulated form and makes it end point for data to send and then TCP helps in transmission or broadcast!

Hub is device to connect two devices, switch is a network bridge which processes and routes data approirately over network layer of OSI Reference model

Let the distance covered be D km. 

 D10+4+ D10-4 = 5

 D14+D6=5

 10D = 42 x 5 = 210

=> D = 21 km

Note : If two trains (or bodies) start at the same time from points A and B towards each other and after crossing they take a and b sec in reaching B and A respectively, then: (A's speed) : (B's speed) = (b : a)

Therefore, Ratio of the speeds of two trains = 9:4 = 3 : 2