Everything sent through an ethernet network is basically cut into small bits of data known as packets. The computer wishing to send information gives the packets an address, and sends them down the cable.
If the packet comes to a hub, then the hub copies the packet and sends it to every other port it has. Once one of the packets gets to the proper destination, the intended recipient sees their address on the packet and accepts it. Those that do not see their address on a packet, discard. With a hub, if systems try to send on the line at the same time then a data collision occurs and the packets must be resubmitted.
A switch is a bit smarter. It learns the addresses of the individual systems. When a packet comes to it, the switch takes a look at the address on it and sends the packet to it's proper destination without sending it to everyone else too. Due to these improvements over the hub, the switch often performs better where high network throughput is desired.
Q. No. :
A binary search tree with node information as 1,2,3,4,5,6,7,8 is given. Write the result obtained on preorder traversal of the binary search tree ?
A conventional computer operating system usually segregates virtual memory into kernel space and user space. Kernel space is strictly reserved for running the kernel, kernel extensions, and most device drivers. In contrast, user space is the memory area where all user mode applications work and this memory can be swapped out when necessary.
Q. No. :
Each character is represented by 7 bits, 1 bit is used to represent error bit and another bit for parity. If total number of bits transmitted is 1200 bits, then what is the number of symbols that can be transmitted ?
The key difference between general-computing operating systems and real-time operating systems is the need for " deterministic " timing behavior in the real-time operating systems. Formally, "deterministic" timing means that operating system services consume only known and expected amounts of time. In theory, these service times could be expressed as mathematical formulas. These formulas must be strictly algebraic and not include any random timing components. Random elements in service times could cause random delays in application software and could then make the application randomly miss real-time deadlines – a scenario clearly unacceptable for a real-time embedded system. Many non-real-time operating systems also provide similar kernel services.
General-computing non-real-time operating systems are often quite non-deterministic. Their services can inject random delays into application software and thus cause slow responsiveness of an application at unexpected times. If you ask the developer of a non-real-time operating system for the algebraic formula describing the timing behavior of one of its services (such as sending a message from task to task), you will invariably not get an algebraic formula. Instead the developer of the non-real-time operating system (such as Windows, Unix or Linux) will just give you a puzzled look. Deterministic timing behavior was simply not a design goal for these general-computing operating systems.
In computer science, a self-balancing (or height-balanced) binary search tree is any node based binary search tree data structure that automatically keeps its height (number of levels below the root) small in the face of arbitrary item insertions and deletions
A router is a piece of networking gear which routes traffic between networks or subnets. Routers function at layer 3, meaning they route based on IP addresses.
Routers use route tables to determine how to route traffic. IP addresses or address ranges are assigned to each interface, and when a packet is routed, the destination address is located in the table so the packet is forwarded out the correct interface.
The gateway router is the connection from your network to the outside world. All traffic not destined for another subnet or segment of the internal network is sent to the gateway and on to its external destination.
The gateway router, like any other router, uses a route table. However, the wildcard or ALL address definition is used, indicating that all traffic not designated as internal gets sent out into the outside world.
The gateway also serves as the access point to your network. From the outside, the only IP address seen is your gateway address. All traffic bound for your network comes into the gateway interface, and is routed internally from there.
Q. No. :
Explain the routines that executes whenever the system boots up like ROM BIOS routines.
Whenever PC is turned ON, BIOS takes the control, and it performs a lot of operations. It checks the Hardware, Ports etc and finally it loads the MBR program into memory (RAM).
Now, MBR takes control of the booting process. Functions of MBR, when there is only one OS is installed in the system are as given below:-
1. The boot process starts by executing code in the first sector of the disk, MBR.
2. The MBR looks over the partition table to find the Active Partition.
3. Control is passed to that partition's boot record (PBR) to continue booting.
4. The PBR locates the system-specific boot files (such as Win98's io.sys or WinXP’s ntoskrnl).
5. Then these boot files continue the process of loading and initializing the rest of the OS.
Scheduling refers to the way processes are assigned to run on the available CPUs, since there are typically many more processes running than there are available CPUs.
Generally scheduler is not a process , it is called each time if the priority of thread changes. The policies of operating system also defines when should be the scheduler called.
A segmentation fault occurs when a program attempts to access a memory location that it is not allowed to access, or attempts to access a memory location in a way that is not allowed (for example, attempting to write to a read-only location, or to overwrite part of the operating system).
Q. No. :
To concatenate two linked lists strings, the order is O(1) is obtained for what kind of list?
A Ping utility is essentially a system administrator's tool that is used to see if a computer is operating and also to see if network connections are intact.
Ping uses the Internet Control Message Protocol (ICMP) Echo function which is detailed in RFC 792. A small packet of information containing an ICMP ECHO_REQUEST is sent through the network to either a particular IP address or a domain name. This packet contains 64 bytes - 56 data bytes and 8 bytes of protocol reader information.
The computer that sent the packet then waits (or 'listens') for a ECHO_REPLY packet from the specified IP address. The ping program then evaluates this reply, and a report is shown. You can check several things with the ping program: can you reach another computer, how long does it take to bounce a packet off of another site. The time taken to Send and Receive a Data Packet is calculated in Milliseconds.
Q. No. :
What data structure would you use to implement a routing table? Suggest optimizations
This can be done using 2 stacks say stack1 and stack2.
1) enQueue() can be implemented using push() on stack1.
2) isEmpty() and isFull() will work similar to stack1's isEmpty() and isFull() functions.
3) deQueue() will be done as following:
a) pop() all elements from stack1 and push() them in stack2( reversing their order from stack1- LIFO to FIFO).
b) Use pop() on stack2 to delete that element.
c) pop() all elements from stack2 and push() them in stack1.
So now deQueue() operation will cost you O(n) than O(1).