Fresh Computer Networks Interview Preparation Guide

Download PDF

yes it can happen. DNS, the Domain Name Service, as you would know, is used to help us resolve Fully Qualified Domain Names (FQDN) to IP addresses. There are different versions of DNS systems running all over the Internet, mainly ranging between Windows (which use the Windows DNS server) and Linux/Unix (using BIND DNS services). Considering there are some very popular Web sites which serve millions of DNS queries per day e.g., Google.com, Hotmail.com, it is logical that these domain names cannot solely rely on one single DNS server, cause if that fails, the whole domain could become unreachable! It is, for this reason, a fault-tolerant DNS service is put in place, which shares the DNS queries amongst several different DNS servers. All servers are configured to either randomly provide clients with IP addresses from a specific pool, or -- by using a round robin method -- cycle between the pool of IP addresses. This is what gives a DNS name multiple IP addresses.

File system is depending on Operation systems & hard Disk sizes.At the time 1990 there were only dos which supports only FAT16 (File allocation table)Upto MS-DOS 6.22 & Windows 3.1 & 3.11 It works only on FAT16FAT16 Has it's limitation that it can't support more than 2.1 GB partition at a time.After that windows 95 & Windows 98That supported FAT16 & FAT32 only. Windows NT supports FAT16 as well as It develops new file systems HPFS i.e. (High Performance File System)
Later i.e. is called as NTFS (New Technology File System)NTFS is now a largest support for us.

Short for virtual LAN, a network of computers that behave as if they are connected to the same wire even though they may actually be physically located on different segments of a LAN VLANs are configured through software rather than hardware, which makes them extremely flexible. One of the biggest advantages of VLANs is that when a computer is physically moved to another location, it can stay on the same VLAN without any hardware reconfiguration.

It remains in the recycler on the drive or partions the held that data untill it is overwriten. To view the recycler you must allow hiden system files to be shown (in Windows this can be done under folder options). There are tool available to recover the deleted data. I recently have used a program call "Recover My files".

The address resolution protocol (ARP) associates an IP address with the physical address. On a typical physical network (eg: LAN) each device on a link is identified by a physical or station address usually imprinted on the network interface card(NIC)Physical addresses can be changed easily, on the other hand IP addresses cannot be changed. ARP is used to find the physical address of the node when its internet address is known.
The reverse address resolution protocol(RARP) allows host to discover its internet address when it known only its physical address. RARP works much like ARP.
To obtain IP address the host first broadcasts an RARP request packet containing its MAC address on the network. All hosts on the network receive the packet, but only the server replier to the host by sending an RARP response packet containing the host's MAC and IP addresses. One limitation with RARP is that the server must be located on the same physical network as the host

The difference between TCP and UDP is connection(TCP) and connectionless(UDP) protocol.Because In TCP for transferring every Packets it needs a acknowledgement packet from reciever ,so if any packet loss happens reciver will not send a acknowledge ment for that packet so Transmitter will once again send the packet.so TCP is reliable connection unless UDP will send a packet and will not expect any acknowledgment from the reciever so it is not reliable.

First u need to specify your network size. Since the network eqiuipments depend upon your sixeeg:
Small network u could use as a l2 switch large network a l3/managed switch.
Same goes for routers and Wan connection.Servers:
1.Active Domain Controller
2.Back up Domain Controller.
3.Dhcp server.
4.Software Update services.
Hope this would suffice...

Serial Advanced Technology Attachment ( is a computer bus primarily designed for transfer of data between a computer and mass storage devices such as hard disk drives and optical drives.The main advantages over the older parallel ATA interface are faster data transfer, ability to remove or add devices while operating (hot swapping), thinner cables that let air cooling work more efficiently, and more reliable operation with tighter data integrity checks.

This is how I share a printer on a the LAN You can print from every PC on your network to one printer. To share a printer with the other PCs in your home you need to configure the PC to which the printer is connected and then install the shared printer on each PC that you want to print from.If you have not already done so, set-up and install the printer onto a PC following the manufacturer's instructions.The following instructions will vary slightly depending on which version of Windows you are using.1. Turn on all of the PCs on your network and turn on the printer.2. Start with the PC to which the printer is connected. Click Start, Settings, Control Panel, Printers.3. In the Printers window, right click on the printer that you want to share on the network and choose "Sharing" from the menu.4. If this is the first time anything has been set-up for sharing on this PC, you may receive a security warning. In the security message, click on "Just enable printer sharing" and then click "OK". Otherwise click on "Share this printer".5. Enter a share name, something like "Laser printer in office". 6. Now click "OK".

Data link layer/Transport layer

Encoding is assigning binary codes according to algorithm, but modulation is changing the properties of one signal(value) according to properties of another signal.

Scandisk is Windows' general-purpose hard drive diagnostic utility. It will find and fix any data errors present on the drive. A "standard" scan checks for any data errors on the drive. A "thorough" scan checks for any data errors on the drive and tests the hard drive for any physical errors. Defrag is Windows' utility for organizing the data structure on the hard drive. Through normal use, the data present on the hard drive becomes scattered across the data area.

1) Check cable between computer and monitor, as well as power to monitor.
2) Boot into safemode - Check status of driver, and run diagnostic on video card. - if no video try putting in a new video card and restart with step 2
3) Restore to previous bootable configuration
4) Re-install OS

A routing protocol is used by router to dynamically find all the networks in the internetwork and to ensure that all routers have the same routing table. Basically routing protocol determines the path of a packet through an internetwork. (eg. RIP, RIPv2, EIGRP and OSPF).A routed protocol can be used to send user data through the established enterprise, when routers know about all networks. Routed protocols are assigned to an interface and determine the method of packet delivery. (eg. IP, IPv6)

simplex- one way transmission.only transmission will takes place here.
duplex- two way transmission.
Both transmission and reception takes place.

2 types of duplex:
1)Half duplex
2)Full duplex

Half duplex:-
both transmission and reception takes place,bt nt at d same time.single channel is used .
Full duplex:-
both txn and recep...takes place simultaneously using 2 different channels. one for txn and other 4 reception.

Seagment is a PDU (Packet Data Unit) of layer 4 transport layer.seagmant is made of
destination port no
senders port no
data
fcs

A ping is normally 64 bytes in size.Many computers can not handle larger than the maximum ip packet size, which is 65,535bytes. Sending a ping of this size can crash the target computer.

POD (Ping of Death) is a type of attack at computer in a network that involves sending of a larger size malicious ping to a computer.

Active Directory is a directory service. The term directory service refers to two things — a directory where information about users and resources is stored and a service or services that let you access and manipulate those resources. Active Directory is a way to manage all elements of your network, including computers, groups, users, domains, security policies, and any type of user-defined objects. It melds several NT services and tools that have functioned separately so far — User Manager for Domains, Server Manager, Domain Name Server — and provides additional functions beyond these services and tools. Active Directory is built around Domain Name System (DNS) and lightweight directory access protocol (LDAP) — DNS because it is the standard on the Internet and is familiar, LDAP because most vendors support it. Active Directory clients use DNS and LDAP to locate and access any type of resource on the network. Because these are platform-independent protocols, Unix, Macintosh, and other clients can access resources in the same fashion as Windows clients.

Switch is a data link layer device that connect multiple LAN segments to form
a single network segment. In switch when we transmit the data first it examine
the data packets for source and destination, then the switch forward the data
packet to the appropriate destination.
Switch minimize the possibility of collision of data packets by reducing
collision domains.
Collision domain are the network segment between two network devices, when
the two devices transmit a data at a time then collision will occur. In such
case both the device stop working. Then it starts to work for a specific period
of time and retransmit the data.
Switches reduces the collision using micro-segmentation.

There are 3 address types in v6 - Unicast, anycast, and multicast. Unicast addresses identify a single network device, anycast and multicast addresses identify a group of network devices. IPv6 addresses are 128 bit, compared to the 32 bit addresses of v4 and look like this example - 2001:0db8:85a3:08d3:1319:8a2e: 0370:7348Ipv6 does not use subnetting.

Logical address of yhe any nic card is ip address of the sysytem.in any copmany lan or wan environment for machine to mechine communication each and every mechine required one nomber.thats why ina peoples desizned and interduces one good technologie is ip addressing system.phisical address of any copmany nic card is also known as a mac address {media accec controler address} mac address mediater bitween cable and mechine. it means mac address main function is transfer the data cable laguage to mechine language anad mechine language to cable language.its a 48 bit address

Advantages All the IP configuration information gets automatically configured for your client machine by the DHCP server. If you move your client machine to a different subnet, the client will send out its discover message at boot time and work as usual. However, when you first boot up there you will not be able to get back the IP address you had at your previous location regardless of how little time has passed. Disadvantage Your machine name does not change when you get a new IP address. The DNS (Domain Name System) name is associated with your IP address and therefore does change. This only presents a problem if other clients try to access your machine by its DNS name.

A port number is a way to identify a specific process to which an Internet or other network message is to be forwarded when it arrives at a server. For the Transmission Control Protocol and the User Datagram Protocol, a port number is a 16-bit integer that is put in the header appended to a message unit. This port number is passed logically between client and server transport layers and physically between the transport layer and the Internet Protocol layer and forwarded on.

Baseband Signalling:
1)Uses digital signalling
2)No frequency-division multiplexing
3)Bi-directional transmission
4)Signal travels over short distances

Broadband Signalling:
1)Uses analog signalling
2)Unidirectional transmission
3)Frequency-division multiplexing is possible
4)Signal can travel over long distances before being attenuated