Top 50 Computer Network Security Interview Questions You Must Prepare 19.May.2024

When hierarchical routing is used, the routers are divided into what we call regions, with each router knowing all the details about how to route packets to destinations within its own region, but knowing nothing about the internal structure of other regions.

The degeneration of a signal over distance on a network cable is called attenuation.

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.

It is any routing protocol used within an autonomous system.

  • Server-based network
  • Peer-to-peer network
  • Peer-to-peer network, computers can act as both servers sharing resources and as clients using the resources.
  • Server-based networks provide centralized control of network resources and rely on server computers to provide security and network administration.

Hybrid devices that combine the features of both bridges and routers.

It is a sequence of lP addresses identifying the route a datagram must follow. A source route may optionally be included in an IP datagram header.

A method for providing fault tolerance by using multiple hard disk drives.

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

The Mount protocol returns a file handle and the name of the file system in which a requested file resides. The message is sent to the client from the server after reception of a client’s request.

The header should have a minimum length of 20 bytes and can have a maximum length of 60 bytes.

A Management Information Base is part of every SNMP-managed device. Each SNMP agent has the MIB database that contains information about the device’s status, its performance, connections, and configuration. The MIB is queried by SNMP.

Class A -
Class B - 191 .255.255.255
Class C -
Class D -
Class E -

10Base2: An Ethernet term meaning a maximum trfer 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.

10Base5: An Ethernet term meaning a maximum trfer rate of 10 Megabits per second that uses baseband signaling, with 5 continuous segments not exceeding 100 meters per segment.

10BaseT: An Ethernet term meaning a maximum trfer rate of 10 Megabits per second that uses baseband signaling and twisted pair cabling.

The attacker is looking for the subnet/network mask of the victim. This would help the attacker to map the internal network.

DNS uses UDP for communication between servers, It is a better choice than TCP because of the improved speed a connectionless protocol offers. Of course, trmission reliability suffers with UDP.

RIP v1 does not use a password for authentication as with Rip v@This makes it possible to attackers to send rogue RIP packets and corrupt the routing table.

It is a protocol formerly used to exchange routing information between Internet core routers.

It is a host that has a multiple network interfaces and that requires multiple IP addresses is called as a Multi-homed Host.

The HELLO protocol uses time instead of distance to determine optimal routing. It is an alternative to the Routing Information Protocol.

External Data Representation is a method of encoding data within an RPC message, used to ensure that the data is not system-dependent.

When the computers on the network simply listen and receive the signal, they are referred to as passive because they don’t amplify the signal in any way. Example for passive topology - linear bus.

A TCB is a complex data structure that contains a considerable amount of information about each connection.

The process that allows a network to self-repair networks problems. The stations on the network notify the other stations on the ring when they are not receiving the trmissions. Beaconing is used in Token ring and FDDI networks.

Routable protocols can work with a router and can be used to build large networks. Non-Routable protocols are designed to work on small, local networks and cannot be used with a router

BQOTP sends a UDP message with a subnetwork broadcast address and waits for a reply from a server that gives it the IP address. The same message might contain the name of the machine that has the boot files on it. If the boot image location is not specified, the workstation sends another UDP message to query the server.

Virtual channel is normally a connection from one source to one destination, although multicast connections are also permitted. The other name for virtual channel is virtual circuit.

Every line has an upper limit and a lower limit on the frequency of signals it can carry. This limited range is called the bandwidth.

The address for a device as it is identified at the Media Access Control (MAC) layer in the network architecture. MAC address is usually stored in ROM on the network adapter card and is unique.

Bit rate is the number of bits trmitted during one second whereas baud rate refers to the number of signal units per second that are required to represent those bits.

baud rate = bit rate / N
where N is no-of-bits represented by each signal shift.

NETBIOS is a programming interface that allows I/O 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 trport protocol designed by microsoft and IBM for the use on small subnets.

A resource record is an entry in a name server’s database. There are several types of resource records used, including name-to-address resolution information. Resource records are maintained as ASCII files.

In a base band trmission, the entire bandwidth of the cable is consumed by a single signal. In broadband trmission, signals are sent on multiple frequencies, allowing multiple signals to be sent simultaneously.

The function of PAD (Packet Assembler Disassembler) is described in a document known as X.@The standard protocol has been defined between the terminal and the PAD, called X.28; another standard protocol exists between hte PAD and the network, called X.2@Together, these three recommendations are often called “triple X”

A pseudo tty or false terminal enables external machines to connect through Telnet or rlogin. Without a pseudo tty, no connection can take place.

Series of interface points that allow other computers to communicate with the other layers of network protocol stack.

It is a simple protocol used to exchange information between the routers.

It is a problem that can ruin TCP performance. This problem occurs when data are passed to the sending TCP entity in large blocks, but an interactive application on the receiving side reads 1 byte at a time.

BUS topology: In this each computer is directly connected to primary network cable in a single line.
Advantages: Inexpensive, easy to install, simple to understand, easy to extend.

STAR topology: In this all computers are connected using a central hub.
Advantages: Can be inexpensive, easy to install and reconfigure and easy to trouble shoot physical problems.

RING topology: In this all computers are connected in loop.
Advantages: All computers have equal access to network media, installation can be simple, and signal does not degrade as much as in other topologies because each computer regenerates it.

Signals are usually trmitted over some trmission media that are broadly classified in to two categories.

Guided Media: These are those that provide a conduit from one device to another that include twisted-pair, coaxial cable and fiber-optic cable. A signal traveling along any of these media is directed and is contained by the physical limits of the medium. Twisted-pair and coaxial cable use metallic that accept and trport signals in the form of electrical current. Optical fiber is a glass or plastic cable that accepts and trports signals in the form of light.

Unguided Media: This is the wireless media that trport electromagnetic waves without using a physical conductor. Signals are broadcast either through air. This is done through radio communication, satellite communication and cellular telephony.

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

A network in which there are multiple network links between computers to provide multiple paths for data to travel.

Wide-mouth frog is the simplest known key distribution center (KDC) authentication protocol.

Telnet is also called as terminal emulation. It belongs to application layer.

Anonymous FTP enables users to connect to a host without using a valid login and password. Usually, anonymous FTP uses a login called anonymous or guest, with the password usually requesting the user’s ID for tracking purposes only. Anonymous FTP is used to enable a large number of users to access files on the host without having to go to the trouble of setting up logins for them all. Anonymous FTP systems usually have strict controls over the areas an anonymous user can access.

It is using a router to wer ARP requests. This will be done when the originating host believes that a destination is local, when in fact is lies beyond router.