1. Differentiate between hub and switch.
a.) Hub is a layer 1 device while Switch is layer 2 device.
b.) Hub works on single collision and single broadcast domain while switch works on per port
collision and single broadcast domain.
2. What is FQDN?
- FQDN is the abbreviation for Fully Qualified Domain Name.
- It contains both the hostname and a domain name.
- It uniquely identifies a host within a DNS hierarchy
3. Tell us something about LMHOSTS files.
- It is a text file that resolves NetBIOS names to IP addresses.
- It can be compared with the HOSTS file which is a static method of resolving domain names
into IP addresses.
- LMHOSTS files must be manually configured and updated.
4. What are the main qualities of an effective and efficient
5. What are 10Base2, 10Base5 and 10BaseT Ethernet LANs?
10Base2 - It is an Ethernet term which means a maximum transfer rate of 10 Megabits per second that
uses baseband signaling, with a contiguous cable segment length of 100 meters and a maximum
of 2 segments.
- It is an Ethernet term meaning a maximum transfer rate of 10 Megabits per second that uses
baseband signaling, with 5 continuous segments not exceeding 100 meters per segment.
- It is an Ethernet term meaning a maximum transfer rate of 10 Megabits per second that uses
baseband signaling and twisted pair cabling.
6. What is anonymous FTP? What is its use?
- It is an FTP that enables the users to connect to a host without a valid login and password.
- The login used is anonymous or guest, with the password usually requesting the user's ID.
- It enables a large number of users to access the files on the host without needing to set up a
login for all of them.
- It exercises a strict control over the areas an anonymous user can access.
7. Which factors mark the reliability of the network?
a. Frequency of failure
b. Downtime / Time taken for recovery.
8. Name the factors that tell us about the security of the
a. Virus attacks on the system.
b. Unauthorized access to the system.
9. Define Bandwidth and Latency?
- Bandwidth/ Throughput – It means the number of bits which can be transmitted over the
network in a specified time.
- Latency – It is the time taken by a message to travel from one side to another.
Bandwidth and latency describe the performance of a network.
10. What is point to point link?
- Direct connection between two computers on a network is called as point to point link.
- No other network devices other than a connecting cable are required for point to point
- The cable connects the NIC card of both the devices.
11. When is a switch said to be congested?
- Sometimes a switch receives the packets faster than they can be accommodated in the shared
link. These packets are stored in the memory for sometime.
- However, after sometime the buffer space will exhaust and some packets will start getting
- The switch is called as congested in this state.
12. Explain a.) Uni-casting, b.) Multicasting and c.)
a.) Uni-casting - Message is sent from a source to a single destination node.
b.) Multicasting - Message is sent from a source to some subsets of other nodes.
c.) Broadcasting - Message is sent from a source to all the nodes in the network.
13. What are the various types of Multiplexing?
The various types of multiplexing are:
a. Frequency Division Multiplexing (FDM)
b. Time Division Multiplexing (TDM)
i. Synchronous TDM
ii. Asynchronous TDM
c. Wave Division Multiplexing (WDM)
14. Which layers of OSI are referred to as network support
The following 3 layers of OSI are referred to as network support layers:
a. Physical Layer
b. Data link Layer and
c. Network Layers
15. Which layers of OSI are referred to as user support
The block of user support layers consists of:
a. Session Layer
b. Presentation Layer and
c. Application Layer
16. What does the Data Link Layer do?
- The Data Link Layer transforms the physical layer to a reliable link.
It takes care of:
a. Node to node delivery.
c. Physical Addressing
d. Flow Control
e. Error Control
f. Access Control
17. What is NIC?
- NIC stands for Network Interface Card.
- It is a peripheral card attached to a PC to helps it connect to a network.
- The MAC address of the card helps the network in identifying the PC.
18. What are the responsibilities of Network Layer?
- The Network Layer aids in source-to-destination delivery of packet across multiple networks.
- It performs:
a. Logical Addressing
19. Name the various error detection methods.
The various error detection methods are:
a. Vertical Redundancy Check (VRC)
b. Longitudinal Redundancy Check (VRC)
c. Cyclic Redundancy Check (VRC)
20. . What is Bit Stuffing?
- Bit stuffing means adding one extra 0 whenever five consecutive 1s follow a 0.
- This is done so that the pattern 0111110 is not mistaken for a flag.
21. How does dynamic host configuration protocol aid in
- In a large set up where it is difficult to manually configure the IP address of each system,
dynamic host configuration protocol comes very helpful.
- Using this protocol, the administrator can create a pool of IP addresses which are called scopes.
These can be then dynamically assigned to the systems.
Routing and Switching
What are Brute Force Attacks?
Brute forcing is a mechanism which is used by an attacker to break the encryption of data by
applying a set of various key.............
How do you use RSA for both authentication and secrecy?
RSA is a public key encryption algorithm. The RSA algorithms are...........
Can you differentiate among encoding, encryption and hashing?
Encoding: Basically encoding is used to protect the integrity of data as it crosses through
communication network to keep its original message.............
If you have to generate a hash function then what characteristics are needed in a secure hash function?
A secure hash function should have the following characteristics:................
What is digital signature? Differentiate between Physical and Digital Signature
A digital signature is an electronic analogue of a written signature; the digital signature can be
used to provide assurance...........
What is Authentication Header and how it provides the protection to IP header?
Basically Authentication Header protects IP header and provides the complete authenticity to the
Explain SSL Protocol. How does it protect internet users from various threats?
The SSL protocol (Secure Socket Layer protocol) was originally developed by Netscape, to
ensure security of data transported.............
What is PIX firewall security? How does it differ from a firewall?
PIX (Private Internet Exchange)...........
What are Malware? Explain different types of Malware
Malware is a software program which is developed to destroy a computer system..............
What are replay attacks? Give an example of replay attack
Replay attacks are the network attacks in which an attacker spies the conversation between the
sender and receiver..........
If you have to ‘encrypt’ as well as ‘compress’ data during transmission then which would you do first and
Data should be transmitted over any communication network in such a way that the data integrity
What is the goal of Information Security in an organization?
Mainly there are three Information security goals in an organization: Confidentiality, Integrity
What is Symmetric-Key cryptography and Asymmetric-Key cryptography?
Symmetric-Key Cryptography: Symmetric-key cryptography uses a single key for both
encryption and decryption. Encryption and decryption algorithm are inverse of each
Explain the services provided by IP (Internet Protocol) - Addressing, Fragmentation, Packet timeouts and
Latest answer: Addressing: For the purpose of delivering datagram packets, IP needs to know
about the address of the destination. By including the host addressing, this task is carried out by
IP. As IP operates in an internet, its systems are designed to accept the addressing of devices
which are unique.............
Explain the classes of IP address
Latest answer: IP addresses are organized into classes. For convenience of humans, IP
addresses are expressed in the decimal format. Every number in each class is represented as
binary to computers..................
Define Broadcast, Unicast and Multicast.
Latest answer: Unicast: A term used in communication to describe a piece of information to
send from one point to another. There are only sender and receiver................
What is Network Mask?
Latest answer: A network mask is used for determination of what subnet an IP address belongs
to. An IP address has network address and the host address.................
Latest answer: A subnet describes a set of networked computers which have common IP
address routing prefix..................
What is the User Datagram Protocol (UDP)?
Latest answer: User datagram protocol allows computer applications to send messages as
datagram packets from source to destination on an Internet Protocol,..................
Explain TCP Windowing concept.
Latest answer: TCP Windowing is a concept that is used for avoiding congestion in the network
What is the Domain Name System (DNS)? What are the advantages of it?
Latest answer: A hierarchical naming system for computer systems, services or for that matter
any resource participating in the internet...................
What is the TTL (Time to Live)? Why is it required?
Latest answer: TTL is a value in data packet of Internet Protocol. It communicates to the
network router whether or not the packet should be in the network for too long or
Explain the use of Internet Control Message Protocol (ICMP)
Latest answer: Internet Control Message Protocol is one of the important protocols in the
Internet Protocol suite. It is mainly used in operating system of networked computers..................
What is the use of IGMP protocol?
Latest answer: 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
What are Ping and Tracert?
Latest answer: 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..............
Explain RSVP. How does it work?
Latest answer: 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...............
Explain the concept of DHCP.
Latest answer: Dynamic Host Configuration Protocol is used assigning IP addresses to
computers in a network. The IP addresses are assigned dynamically...............
What are the differences between a domain and a workgroup?
Latest answer: 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.............
Explain how NAT works.
Latest answer: 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................
What is PPP protocol? Explain PPP packet format.
Latest answer: 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................
What is IP Spoofing and how can it be prevented?
Latest answer: 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...............
Explain IP datagram, Fragmentation and MTU.
Latest answer: IP datagram can be used to describe a portion of IP data. Each IP datagram has
set of fields arranged in an order. The order is specific which helps to decode and read the stream
What is an application gateway?
Latest answer: An application gateway is an application program that runs on a firewall
between two networks. An application gateway is used for establishing connection between
client program and destination service..................
Explain Circuit Level Gateway.
Latest answer: A circuit level gateway is used to find if a session in TCP handshaking is
legitimate or not. It can be considered as a layer between application layer and transport
What is 'Gateway Of Last Resort'?
A Gateway of Last Resort or Default gateway is a route used by the router when no other known
route exists to transmit the IP packet. Known routes are present in the routing table.................
What are switches? Explain the concepts of Layer-3 switches.
Latest answer: It is a device that connects multiple network segments.
A switch analyzes the MAC address and then determines where to send the data..............
What is Router? Explain components of Routers.
Latest answer: The way switches connect multiple computers, a router connects multiple
networks. Routers comprise of data consisting of large tables of networks and
Overview of OSI layer.
Latest answer: OSI stands for Open Systems Interconnection
The OSI reference model gives an overview of the layered communications and computer
network protocol design...................
Explain different layers in the OSI model.
Latest answer: Application Layer: Closest to the end user, Interact directly with the software
Presentation Layer: Translates application to network format, and vice versa, Works to transform
data into the form that the application layer can accept, Formats and encrypts data to be sent
across a network.........................
Explain the concept and capabilities of Unicast IP Addresses.
Latest answer: It is an IP address that uniquely identifies a host in a network.
The datagram with a unicast IP address is received and processed by only a single host.
What is IP Multicasting?
Latest answer: It is an IP address that identifies a particular group of hosts in network.
This group of hosts is called a multicast group..............
Explain the classes of IP addresses. Why do we need them?
Latest answer: Class A:
Range: from 0.0.0.0 to 127.255.255.255.
Leftmost bit: 0.
First 8 bits: netid.
Remaining 24 bits: hostid..............
What is Subneting? Explain the advantages of using Subneting.
Latest answer: Subneting is dividing a network into several subnets.
This is usually done for the following purposes:..................
What is Superneting? Explain the concept of custom Subneting.
Latest answer: Supernetting or Classless Inter-Domain Routing (CIDR) : It is a way to
aggregate multiple Internet addresses of the same class..............
What is VLSM, Variable length subnet masking?
Latest answer: VLSM is a means of allocating IP addressing resources to subnets according to
their individual need rather than some general network-wide rule................
What is Data Fragmentaion? Explain how Data Fragmentaion works.
Latest answer: Fragmentation occurs when storage space is used inefficiently due to which
storage capacity and performance is reduced................
Explain the concepts and capabilities of IP Datagram.
Latest answer: Data transmitted over an internet using IP is carried in messages called IP
datagrams. Like all network protocol messages, IP uses a specific format for its
What is MAC address?
Media Access Control address is an identifier for assigned to most network adapters or Network
Interface Cards by the manufacturer for the purpose of identification...............
Describe the Packet Format of ARP (Address Resolution Protocol)?
The fields of the packet format of ARP are as follows:
-Hardware type: It is a 16-bit field . Each LAN has been assigned an integer based on its type.
For example, Ethernet is given the type 1.
-Protocol type: This is a 16-bit field defining the protocol. For example, the value of this field for
IPv4 protocol is 0800.
-Hardware length: This is an 8-bit field defining the length of the physical address in bytes. For
example, for Ethernet the value is 6.
-Protocol length: This is an 8-bit field defining the length of the logical address in bytes. For
example, for IPv4 protocol the value is 4.
-Operation: This is a 16-bitfield defining the type of packet. Two packet types are defined: ARP
request (1), ARP reply (2).
-Sender hardware address: This is a variable-length field defining the physical address of the
sender. For example, for Ethernet this field is 6 bytes long.
-Sender protocol address: This is a variable-length field defining the logical (for example, IP)
address of the sender. For the IP protocol, this field is 4 bytes long.
-Target hardware address: This is a variable-length field defining the physical address of the
target. For example, for Ethernet this field is 6 bytes long.
-Target protocol address: This is a variable-length field defining the logical (for example, IP)
address of the target. For IPv4 protocol, this field is 4 bytes long.
What are the advantages of IPv6 over IPv4?
the next generation IP, or IPv6 has some advantages over IPv4 that can be summarized as
- Larger Address Space: An IPv6 address is 128 bytes long where IPv4 has 32-bit address only,
this is a huge increase in the address space.
- Better Header Format: IPv6 uses a new header format which simplifies and speeds up the
routing process because most of the options do not need to be checked by routers.
- New Options: IPv6 has new options to allow for additional functionalities.
- Allowance for extension: In IPv6 new technologies can easily embedded.
-Support For Resource Allocation: In IPv6, flow label has been added to enable the source to
request special handling of the packet. This mechanism can be used to support traffic such as
real-time audio and video.
-Support For More Security: The encryption and authentication options in IPv6 provide
confidentiality and integrity of the packet.
What are the different design goals of ATM?
Asynchronous Transfer Mode (ATM) is the cell relay protocol.
The Design Goals of ATM are as follows:
- A technology is needed to take advantage of high rate transmission media and less susceptible
to noise degradation for maximizing the data rates.
-The system must interface with existing systems and provide wide-area inter-connectivity
-The implementation of design must be cheaper enough so that everyone can afford it. If ATM is
to become the backbone of international communications, as indeed, it must be available at low
cost to every user who wants it.
-The new system must be able to work with and support the existing telecommunication
- The new system must be connection-oriented to ensure accurate and predictable delivery.
- One objective is to move as many of the functions to hardware as possible (for speed) an
eliminate as many software functions as possible (again for speed).