Important MCSE Interview Questions Part – 2

1.What are Ping and Tracert?

Ping and tracert are the commands used to send information to some remote computers to receive some information. Information is sent and received by packets. Ping is used to check if the system is in network or not. It also gives packet lost information. In windows ping command is written as ping ip _address.

Tracert is called as trace route. It is used to track or trace the path the packet takes from the computer where the command is given until the destination. In windows ping command is written as tracert ip_address .

2.Explain RSVP. How does it work?

Resource Reservation protocol is used to reserve resources across a network. It is used for requesting a specific Quality of Service (QoS) from the network. This is done by carrying the request (that needs a reservation of the resource) of the host throughout the network.

It visits each node in the network. <>p RSVP used two local modules for reservation of resources. Admission control module confirms if there are sufficient available resources while policy module checks for the permission of making a reservation.

RSVP offers scalability. On a successful completion of both checks RSVP uses the packet classifier and packet scheduler for the desired Qos requested.

3.Explain the concept of DHCP.

Dynamic Host Configuration Protocol is used assigning IP addresses to computers in a network. The IP addresses are assigned dynamically.

Certainly,using DHCP,the computer will have a different IP address every time it is connected to the network. In some cases the IP address may change even when the computer is in network. This means that DHCP leases out the IP address to the computer for some time. Clear advantage of DHCP is that the software can be used to manage IP address rather than the administrator.

4.What are the differences between a domain and a workgroup?

In a domain,one or more computer can be a server to manage the network. On the other hand in a workgroup all computers are peers having no control on each other. In a domain,user doesn’t need an account to logon on a specific computer if an account is available on the domain.

In a work group user needs to have an account for every computer. In a domain,Computers can be on different local networks. In a work group all computers needs to be a part of the same local network.

5.What is the use of IGMP protocol?

Internet Group Management Protocol: – It allows internet hosts to participate in multicasting. The IGMP messages are used to learn which hosts is part of which multicast groups. The mechanism also allow a host to inform its local router,that it wants to receive messages.

6.Explain how NAT works.

Network Address Translation translates and IP address used in a network to another IP address known within another network. A NAT table is maintained for global to local and local to mapping of IP’s. NAT can be statically defined or dynamically translate from a pool of addresses.

The NAT router is responsible for translating traffic coming and leaving the network. NAT prevents malicious activity initiated by outside hosts from reaching local hosts by being dependent on a machine on the local network to initiate any connection to hosts on the other side of the router.

7.What is PPP protocol?

Point to Point protocol helps communication between 2 computers over a serial cable,phone line or other fiber optic lines. E.g. Connection between an Internet Service Provider and a host. PPP also provides authentication.

PPP operates by sending Request packets and waiting for Acknowledge packets that accept,reject or try to change the request. The protocol is also used to negotiate on network address or compression options between the nodes.

8.Explain PPP packet format.

Dynamic Host Configuration Protocol is used assigning IP addresses to computers in a network. The IP addresses are assigned dynamically. Certainly,using DHCP,the computer will have a different IP address every time it is connected to the network.

In some cases the IP address may change even when the computer is in network. This means that DHCP leases out the IP address to the computer for some time. Clear advantage of DHCP is that the software can be used to manage IP address rather than the administrator.

9.What is IP Spoofing and how can it be prevented?

IP spoofing is a mechanism used by attackers to gain unauthorized access to a system. Here,the intruder sends messages to a computer with an IP address indicating that the message is coming from a trusted host. This is done by forging the header so it contains a different address and make it appear that the packet was sent by a different machine.

Prevention:-

Packet filtering: –

to allow packets with recognized formats to enter the network Using special routers and firewalls. Encrypting the session

10.Explain IP datagram.

IP datagram can be used to describe a portion ofIP data. Each IP datagram has set of fields arranged in an order. The order is specific which helps to decode and read the stream easily. IP datagram has fields like Version,header length,Type of service,Total length. checksum,flag,protocol,Time to live,identification,source and destination ip address,padding,options and payload.

11.What is difference between TCPIIP and UDP?

TCP – Transfer Control Protocol:

Reliable
Connection oriented
Acknowledgement

UDP – User Datagram Protocol:

Non reliable
Connectionless
No Acknowledgement

12.What is NVT (Network Virtual Terminal)?

It is a set of rules defining a very simple virtual terminal interaction. The NVT is used in the start of a Telnet session.

13.What is SLIP (Serial Line Interface Protocol)?

It is a very simple protocol used for transmission of IP datagrams across a serial line.

14.What is Kerberos?

It is an authentication service developed at the Massachusetts Institute of Technology. Kerberos uses encryption to prevent intruders from discovering passwords and gaining unauthorized access to files.

15.What are NETBIOS and NETBEUI?

NETBIOS is a programming interface that allows 1/0 requests to be sent to and received from a remote computer and it hides the networking hardware from applications. NETBEUI is NetBIOS extended user interface. A transport protocol designed by Microsoft and IBM is for the use on small subnets.

16.What is Frame Relay?

Frame relay is high-speed data communication technology that operates at the physical and data link layers of the OSI model.Frame relay uses frames for data transmission in a network.

17.What is Virtual Private Network (VPN) and how does it work?

VPN or virtual private network is used to connect two networks by means internet. VPN uses PPTP (point-to-point tunneling protocol) and other security procedures to make a secure tunnel on internet.

18.What is a RAS server?

RAS or remote access server allows you to remote dial in through the desktop computers,laptops,and GSM mobile phones.

19.What is a Frame Relay?

Frame relay is high-speed data communication technology that operates at the physical and data link layers of the OSI model. Frame relay uses frames for data transmission in a network.

20.What is packet filter?

Packet filter is a standard router equipped with some extra functionality. The extra functionality allows every incoming or outgoing packet to be inspected. Packets meeting some criterion are forwarded normally. Those that fail the test are dropped.

21.What is Subnet Mask?

A subnet mask is used to determine the number of networks and the number of host computers. Every class of the IP address uses the different range of the subnet mask. Subnet masks allow the IP based networks to be divided into the sub networks for performance and security purposes.

22.What is an IP Address?

An IP address is a unique identifier of a computer or network device on the local area network,WAN or on internet. Every host computer on the internet must have a unique IP address. IP addresses on the internet are usually assigned by the local ISPs to which users are connected.

23.What is WiFi?

WiFi or wireless fidelity is a base-band network technology that is used for the wireless data communication.

24.What is LDAP?

Lightweight Directory Access Protocol is used to access the directory services from the Active directory in Windows operation systems.

25.What are the standard port numbers for SMTP,POP3,IMAP4,RPC,LDAP,and FTP?

SMTP – 25,POP3 – 110,IMAP4 – 143,RPC – 135,LDAP,FTP-21,HTTP-80

26.How Gateway is different from Routers?

A gateway operates at the upper levels of the OSI model and translates information between two completely different network architectures or data formats.

27.What is the difference between bit rate and baud rate?

Bit rate is the number of bits transmitted during one second whereas baud rate refers to the number of signal units per second that are required to represent those bits. Baud rate= bitrate/N where N is no of bits represented by each signal shift.

28.What is TCP windowing concept?

TCP windowing concept is primarily used to avoid congestion in the traffic. It controls the amount of unacknowledged data. A sender can send before it gets an acknowledgement back from the receiver that it has received it.

29.What is the Public Key Encryption?

Public key encryption use public and private key for encryptioin and decryption. In this mechanism,public key is used to encrypt messages and only the corresponding private key can be used to decrypt them. To encrypt a message,a sender has to know reciepients public key.

30.What is Data Encryption?

Data encryption ensures data safety and very important for confidential or critical data. It protect data from being read,altered or forged while transmission.