Top 50 🔥 Network Administrator Interview Questions and Answers
Summary
TLDRThis video script by Lauren offers an informative guide to the top 50 interview questions for aspiring network administrators. It covers essential IT concepts such as firewalls, VPNs, IP addresses, DNS, and network topologies. The script also delves into the OSI model, network devices like routers and switches, and security topics like DoS attacks and encryption. Additionally, it touches on practical aspects of networking, including troubleshooting, VLANs, and the use of tools like ipconfig and SNMP. The content is designed to help IT professionals prepare for interviews and enhance their understanding of network administration.
Takeaways
- 🔒 A firewall is a security system that prevents unauthorized connections between networks, using either software or hardware implementations.
- 🌐 The difference between HTTP and HTTPS is that HTTP is the standard protocol for transmitting website data over the internet (using TCP port 80), while HTTPS is a secure version that adds encryption and identity verification (using TCP port 443).
- 🛡️ A VPN (Virtual Private Network) provides a secure connection over public networks like the internet, often used by remote workers to access their company's network securely.
- 📍 IP addresses are categorized into public and private addresses; public IPs are routable on the internet, while private IPs are used for internal networks and are not internet-routable.
- 🔄 DNS (Domain Name System) translates domain names into IP addresses, acting as the internet's phone book to locate and access internet resources.
- 🚀 The default route in networking is a configuration that establishes packet forwarding rules when no specific next hop address is available.
- 🔄 DHCP (Dynamic Host Configuration Protocol) automates the assignment of IP addresses to network devices, eliminating the need for manual IP address allocation.
- 💥 A DoS (Denial of Service) attack aims to make network services or the internet unavailable to users, often by overwhelming a web server with traffic.
- 🌐 Network topology refers to the physical and logical layout of a network, including how devices and cables are connected.
- 🛠️ A router is a networking device that manages data flow between connected devices and segments, forwarding data packets based on their destination.
- 📈 The OSI reference model has seven layers, each with specific functions, that define how applications communicate within a network.
Q & A
What is the primary function of a firewall?
-A firewall's primary function is to prevent connections between two or more sources by blocking any incoming or outgoing traffic, enhancing network security.
What are the two forms of firewalls and how do they differ?
-Firewalls come in two forms: software firewalls, which are programs that provide network security features, and hardware firewalls, which are physical devices that act as a barrier between a trusted network and an untrusted network.
Explain the difference between HTTP and HTTPS protocols.
-HTTP (Hypertext Transfer Protocol) is used for transmitting website data and allows for the use of hyperlinks, operating over TCP port 80. HTTPS (HTTP Secure) is a secure version of HTTP that provides identity verification and encryption, using TCP port 443.
What is a VPN and why is it commonly used?
-A VPN (Virtual Private Network) is a service that allows users to create a secure connection over public networks like the internet. It is commonly used by remote workers to access their company's network securely from different locations.
What are the two types of IP addresses and what are their purposes?
-There are two types of IP addresses: public and private. Public IP addresses are used to access the internet and are routed on the internet, while private IP addresses are used for internal networks and are not routed on the internet, ensuring that traffic cannot be sent to them from the outside.
What is DNS and how does it function?
-DNS (Domain Name System) is like the phone book of the internet. It translates domain names, like www.google.com, to IP addresses that browsers can use to load internet resources through the IP protocol.
What is the role of DHCP in a network?
-DHCP (Dynamic Host Configuration Protocol) is responsible for automatically assigning IP addresses to network devices, eliminating the need for manual IP address allocation and reducing the potential errors associated with manual configuration.
What is a DoS attack and how is it executed?
-A DoS (Denial of Service) attack is an attempt to prevent users from accessing the internet or network services. It is often executed by hackers who overload a web server, making it unable to process legitimate traffic and rendering any website on that server inaccessible.
Explain the concept of network topology.
-Network topology refers to the physical and logical layout of a computer network. It defines how computers, devices, and cables are connected to each other, providing a visual representation of the network's structure.
What is a router and how does it manage data flow?
-A router is a network device that manages the flow of data to multiple connected devices. It connects two or more network segments and transfers information from the source to the destination. Routers use data packets and routing tables to determine the best path for forwarding data.
What are the seven layers of the OSI reference model and how do they facilitate communication?
-The OSI (Open System Interconnection) model has seven layers: Physical, Data Link, Network, Transport, Session, Presentation, and Application. Each layer provides specific functions that facilitate communication between applications within a network, ensuring that data is transmitted and received correctly.
Outlines
🔒 Network Security and Protocols
This paragraph introduces the video's focus on top 50 network administrator interview questions, with the first few addressing network security and protocols. It explains what a firewall is and its role in blocking incoming and outgoing traffic, the difference between HTTP and HTTPS protocols, and the use of VPNs for secure remote access. Additionally, it covers the basics of IP addresses, DNS, default routes, DHCP, DoS attacks, and network topology, providing foundational knowledge for IT professionals.
🌐 Network Models and Technologies
The second paragraph delves into network models and technologies, starting with the OSI reference model and its seven layers, which facilitate communication between network applications. It then discusses the WAN technology suitable for a company's global connectivity needs, the role of proxy servers in network security, the localhost concept, MAC addresses, data encapsulation, and network management through SNMP. The paragraph also touches on the different types of networks based on size, such as LANs, MANs, and WANs, and defines round trip time (RTT) as a key network performance metric.
🔧 Network Devices and Configuration
This section focuses on network devices and their configuration, explaining the function of a router in managing data flow and the use of IP packets and routing tables. It introduces the concept of data encapsulation in computer networks, the use of IPconfig and ifconfig commands for network interface configuration, and the SNMP for device management. The paragraph also discusses the three types of networks based on size, the importance of the OSI model for protocol layering, and the distinction between MAC addresses and IP addresses in networking.
🌟 VLANs, Subnets, and Network Management
The fourth paragraph emphasizes VLANs and subnets in network management, detailing how VLANs work at the data link layer to separate network traffic and how subnets are composed of IP addresses and subnet masks. It addresses common HTTP status codes, the smallest IPv4 subnet mask for a network of up to 30 devices, packet filtering as a firewall technique, and the advantages of reverse proxy servers. The paragraph also clarifies the roles of routers and gateways in network traffic regulation and the function of DNS records in mapping domain names to IP addresses.
📈 Network Performance and Career Development
The final paragraph discusses network performance, with a focus on the number of network IDs in a class C network and the host IDs per network ID. It explores practical scenarios like file sharing between two computers without a hub or router, secure CLI sessions with Cisco switches, and the use of TCP/IP protocol stack for datagram replies. The paragraph concludes with questions about open source project contributions, handling technical mistakes, staying updated with technical news, resolving disagreements in a team, and factors affecting network throughput.
🚀 Career Development Resources
This closing paragraph provides a brief call to action for viewers to check out more information and resources to help develop their IT careers, suggesting further exploration of topics covered in the video.
Mindmap
Keywords
💡Firewall
💡HTTP and HTTPS Protocols
💡VPN (Virtual Private Network)
💡IP Addresses
💡DNS (Domain Name System)
💡Default Route
💡DHCP (Dynamic Host Configuration Protocol)
💡DoS (Denial of Service) Attack
💡Network Topology
💡Router
💡OSI Model
Highlights
Firewalls can be either software or hardware and are used to block incoming or outgoing traffic.
HTTP and HTTPS protocols differ in that HTTPS is a secure version of HTTP with identity verification and encryption.
A VPN allows secure connections over public networks, commonly used by remote workers to access their company's network.
IP addresses are divided into public and private groups; public IP addresses route on the internet while private addresses are for local networks.
DNS translates domain names to IP addresses, acting as the internet's phone book.
A default route in IP configuration establishes forwarding rules for packets when no specific next hop address is available.
DHCP automates the assignment of IP addresses to network devices, eliminating manual allocation errors.
DOS attacks aim to prevent users from accessing the internet or network services, often by overloading web servers.
Network topology defines the physical layout of a computer network and how devices are connected.
Routers manage data flow between network segments and are essential for transferring information from source to destination.
The OSI reference model has seven layers and defines how applications communicate within a network.
WAN technology is recommended for a company expanding globally to keep all branches connected 24/7.
A proxy server protects the network by preventing unauthorized access to internal IP addresses.
127.0.0.1, or localhost, is the loopback address used to establish a connection with one's own computer for testing purposes.
MAC addresses are unique, permanent identifiers for network hardware, unlike IP addresses which can change.
Data encapsulation in networking involves adding headers to packets for transmission between computers.
IPConfig and ifconfig commands are used to view and configure network interface settings on Windows and Unix-based systems, respectively.
SNMP is a protocol for managing and exchanging information between network devices like switches, routers, and printers.
Networks can be categorized by size into LANs, MANs, and WANs, each covering different geographic areas and numbers of devices.
Round trip time (RTT) measures the time for a signal to reach its destination and return with an acknowledgement.
Encryption and decryption are processes used to secure data transmission by converting data to unreadable forms and back to original forms.
Transcripts
hi everyone in this video i'm going to
show you
the top 50 network administrator
interview questions and answers
my name is lauren and this channel is
all about showing you how to become
a highly paid itpro fast
let's get started
[Music]
question number one what is a firewall
a firewall prevents connection between
two or more sources
it basically blocks any incoming or
outgoing traffic
firewalls come in two forms software or
hardware firewalls
question number two can you explain the
difference between
http and https protocols
http stands for hypertext transfer
protocol
and is used by the majority of websites
as a means of transmitting website
data and it allows for the use of
hyperlinks
this protocol uses tcp port 80.
https is a secure version of the http
protocol that allows for identity
verification
and low level encryption using tc port
443 question number three
what is a vpn a vpn
is a virtual private network it allows
users to create a secure connection over
public networks such as the internet
vpns are commonly used by mobile workers
in order to access their company's
network from remote locations
question number four what are two types
of ip addresses
and what are they used for all ipv4 ip
addresses can be divided into two
major groups public and private ip
addresses a
public ip address is an ip address that
is used to access the internet
public ip addresses are routed on the
internet
private internal ip addresses are not
routed on the internet and traffic
cannot be sent to them from the internet
they are only supposed to work within
local networks
question number five what is dns
dns stands for domain name system
it is basically the phone book of the
internet
dns translates domain names for example
www.google.com or www.youtube.com
to ip addresses so browsers can load
those
internet resources through the internet
protocol
question number six what is a default
route
a default route is a configuration of
the internet protocol
ip that establishes a forwarding rule
for packets when no specific address of
a next hop host
is available from the routing table or
other routing mechanism
question number seven what is dhcp
and what is it used for dhcp
stands for dynamic host configuration
protocol
and it automatically assigns ip
addresses to network devices
it completely removes the process of
manual allocation of ip addresses
and reduces the errors caused due to
this
question number eight what is dos
dos or denial of service attack is an
attempt to prevent users from being able
to access the internet
or any other network services such
attacks
may come in different forms and are
commonly performed by hackers
one common method of doing this is to
overload a web server so that it can no
longer process legitimate traffic
any website on this web server then
becomes inaccessible
question number nine what is network
topology
network topology is a physical layout of
the computer network
and it defines how the computers devices
cables etc
are connected to each other question
number 10
what is a router a router is a device
that manages the flow of data to
multiple connected devices
it is a network device that connects two
or more network segments
it is used to transfer information from
the source to the destination
in simple words the cable coming from
your isp
goes into a modem which converts input
signals into digital data
usable by a computer a router connects
your modem with other devices to allow
communication between those devices
and the internet routers send
information in the form of data packets
when a router receives a packet it
checks its routing table to determine if
the destination address is for a system
on one of its attached networks or if
the message must be forwarded to another
router
when packets are forwarded from one
router to another router
the receiving router reads the network
address in the packets
and identifies the destination network
and repeats the process
mentioned above question number 11 what
is the osi reference model and how many
layers does it have
the open system interconnection model is
a conceptual reference model that
defines how applications communicate
with each other within a network
it also helps you to understand the
relationship between networks
and defines the process of communication
in a network
it has seven layers question number 12
let's say a company is expanding its
business to other countries
it wants all of its branches to remain
connected to its corporate headquarters
24
7. which network technology do you think
they should use
they should use a wan question number 13
what is a proxy server and how do they
protect the computer network
all devices on a network have an ip
address
knowing the exact ip address of a
network device can leave that device
exposed to an attack proxy servers
prevent unauthorized external users from
accessing those internal ip addresses it
makes the computer network
virtually invisible to external users
question number 14
what is meant by 127.0.0.1
localhost simply put localhost is the
default name
used to establish a connection with your
own computer using the loopback address
network
think of loopback as looping back to
your own machine
the loopback address network has a
default ip address of 127.0.0.1
localhost is used to test applications
on a local computer
when you move to a production or remote
server you will change the references
from localhost to the domain name
you are using the ip address 127.0.0.1
is reserved for loopback or localhost
connections
these networks are usually reserved for
the biggest customers
or some of the original members of the
internet
to identify a connection issue the
initial troubleshooting step
is to ping the server and check if it is
responding
127.0.0.1 and
localhost are the same things in most of
the computer network
question number 15 what is a mac address
a mac address is a unique device address
given to
every network connected hardware unlike
ip addresses
mac addresses are permanent every
network connected device has
one and only one mac address mac stands
for
media access control it is a unique
48-bit serial number
burned into the network circuitry of
every ethernet and wi-fi device
question number 16 what is data
encapsulation
in a computer network to enable data
transmission from one computer to
another
the network devices send messages in the
form of packets
these packets are then added with the ip
header by the relevant osi
reference model layer the data link
layer encapsulates each packet
in a frame that contains the hardware
address of the source
and the destination computer if a
destination computer is on a remote
network
then the frames are routed through a
gateway or router to the destination
computer
question number 17 what is ipconfig
and ifconfig ipconfig stands for
internet protocol configuration
and is a command used on microsoft
windows to view and configure the
network interface
the command ipconfig is useful for
displaying
all tcp ip network information currently
available on a network
it also helps to modify the dhcp
protocol
and dns settings ifconfig
also known as interface configuration is
a command that is used on linux
mac and unix operating systems
it is used to view and configure the tcp
ip network interface parameters from the
command line
question number 18 what is snmp
snmp stands for simple network
management protocol
it is a protocol used for collecting
organizing and exchanging
information between network devices snmp
is widely used in network management for
configuring network devices like
switches
hubs routers printers and servers
question number 19 explain three types
of networks
based on their sizes the size of a
network is defined by the geographic
area it covers and the number of
computers or
network devices within it three types of
networks based on their size
are local area network lan
a network with a minimum of two
computers to a maximum of
thousands of computers within an office
or a building
is known as a lan generally it works for
a single site where people can share
resources like printers data storage
and more metropolitan area network
man it is larger than a land and used to
connect
various lands across small regions a
city
campus of colleges or universities and
the like
which in turn forms a larger network
wide area network
when multiple lands and mans connected
together
form a wan it covers a wider area like a
whole country or
the world question number 20 define
round trip time the time taken for a
signal to reach the destination
and travel back to the sender with the
acknowledgement is termed as
round trip time rtt it is also called
round trip delay rtd question number 21
what is encryption and decryption
encryption is the process of converting
transmitted data into a form that cannot
be read by any device
other than the intended recipient
decryption
is the process of converting back the
encrypted data to its original form
an algorithm called a cipher is used in
the encryption
and decryption process question number
22
mention two important actions performed
by a cisco switch
it uses the source mac addresses of
frames
to build and maintain a mac address
table
it also utilizes the mac address table
to forward frames via the destination
mac address
question number 23 what is a link
a link refers to the connectivity
between two devices
it includes the type of cables and
protocols used for one device to be able
to communicate with the other
question number 24 briefly describe
nat nat stands for network
address translation this is a protocol
that provides a way for
multiple computers on a common network
to share a single connection to the
internet
question number 25 what is rip
rip short for routing information
protocol
is used by routers to send data from one
network to another
it efficiently manages routing data by
broadcasting its routing table to
all other routers within the network it
determines the network distance
in units of hops question number 26
you have one 48 port switch with three
vlans how many collision domains and how
many broadcast domains
three broadcast domains and 48 collision
domains
question number 27 draw a diagram of a
network you've worked on and please
explain it to me this is one of the most
common questions
asked in network administrator
interviews this question will test your
problem solving skills
confidence and work experience check out
lucidchart's networking diagramming tips
and draw
simple and complex networks for practice
a link to lucidchart's website will be
listed in the description area
under this video question number 28
what's the most important thing about
the osi model
the most important factor about the osi
model
is that we can divide up the protocols
into layers
another key factor is that the layers of
the osi model
provide encapsulation and abstraction
question number 29 can you name the
layers of the osi model
physical data link network transport
session presentation and application
question number 30 why can't mac
addresses be used instead of ipv4
or ipv6 for networking unlike
ip addresses mac addresses do not
specify
unique destinations for communication
an ip scheme can be used for a group of
computers to logically distinguish them
as a group via routing tables these
groups can be divided into multiple
levels so that we don't have to keep
track
of every single subnet for instance
17.x.x.x is within the apple network
using an ip scheme helps apple to keep
track of where each of its
thousands of subnets is located and how
to get to them
that's not possible with mac addresses
question number 31
explain the difference between a vlan
and a subnet
do you need a vlan to set up a subnet
vlans work at the data link layer
they refer to the 802.1q standard
using vlans you can give ports a unique
mac address table
separating them from each other vlans
can transport one
or more subnets a vlan is used for
switch partitioning
for example let's assume that you have
an eight port switch
you can use vlans and assign four ports
to one
vlan vlan one and four ports to another
vlan
vlan 2. vlan 1 is totally separated from
vlan 2 traffic
and vice versa on a logical basis you
can get two switches using this
technique
usually if a switch hasn't seen a mac
address
it will flood the traffic to all other
ports
vlans prevent this a subnet is a range
of ip addresses determined by part of an
address
often called network address and a
subnet mask
netmask in simple words a subnet is a
small network
composed by a group of ip addresses
subnets communicate with each other
using routers
question number 32 mention some common
http
status codes 1xx informational responses
communicates transfer protocol level
information
2xx success indicates that the client's
request was accepted successfully
3xx redirection indicates that the
client must take some additional action
in order to complete their request
4xx client-side error
this category of error status codes
points the finger at clients
5xx server-side error the server takes
responsibility for these error status
codes
question number 33 what is the smallest
ipv4 subnet mask
that can be applied to a network
containing up to 30 devices
if you have a standard slash 24 vlan for
users
a 30 for point-to-point links and a
network of up to 30 devices
the smallest ipv4 subnet mask
would be a 27 or a subnet mask
of 255.255.2
question number 34 what is a packet
filter
and how does it work a packet filter is
used as a firewall technique
to control network access by monitoring
outgoing
and incoming packets packets are checked
based on their source
and destination ip addresses protocols
and ports packet filtering is used for
modest
security requirements it is used for
providing isolation of one subnet
from another question number 35
what are the advantages of using a
reverse proxy server
a reverse proxy server will hide the
topology and characteristics of your
servers
it also helps with load balancing
because reverse proxy servers enforce
algorithms like round robin weighted
round robin
and weighted least connections some
other advantages
include ssl offloading and termination
question number 36 can you explain the
difference between
a router and a gateway gateways are used
to regulate
traffic between two dissimilar networks
while routers regulate traffic between
similar networks
let's say you have a windows 2000
network
which uses tcp ip as its primary
protocol
you can connect your network with the
internet using a router
because the internet also uses tcp ip as
its primary protocol
on the other hand you'd use a gateway to
connect a pc network with a 3270
mainframe environment
or to connect a windows nt network with
a netware network
question number 37 what is a default
gateway
a default gateway serves as an access
point
for outbound connections to other
networks
it allows one computer to communicate
with another computer on a different
network
question number 38 can you tell me how
dns records work
dns records tell the dns server which ip
address
each domain is associated with it also
tells how to handle requests
sent to each domain dns records are
basically
mapping files dns records use specific
syntax for its configurations and
functions
some important dns records are soa
start of authority records a address
mapping records
aaa ip version 6 address records
cname canonical name records mx
mail exchanger records ns
name server records ptr
reverse lookup pointer records question
number 39
what is the number of network ids in a
class c
network the number of network id bits in
a class c network is 24.
the number of possible network ids is 2
raised to 21 or 2 million
97 152
the number of host ids per network id is
2
raised to 8 -2 or 254
question number 40 a user in your
company wants to connect two computers
for file sharing
is it possible to do this without using
a hub or
router yes you can use a crossover cable
in this situation
the data transmit pin of one cable is
connected to the data receive pin
of the other cable and vice versa
question number 41
which connection provides a secure cli
session
with encryption to a cisco switch an
ssh connection question number 42
let's say a user opens three browsers on
his pc to access
www.cisco.com to search for ccna
information
the cisco web server sends a datagram as
a reply to the request from one of the
web browsers
can you tell which information is used
by the tcp
ip protocol stack on the user machine to
identify which of the three web browsers
should receive the reply
yes you can use the destination port
number
question number 43 where are cisco ios
debug output messages sent by default
they are sent to the console line
question number 44
let's say a network administrator issues
a copy running dash config startup dash
config command
after making configuration changes on a
cisco switch
what would be the impact of these
commands the new configuration will be
loaded if the switch is restarted
question number 45 do you contribute to
any open source projects
contributing to open source projects
will help you expand your network and
pass
a lot of interviews always say yes
if it's true when asked this question
because the employer would feel that you
are enthusiastic about network
administration
and also willing to share your knowledge
contributing to open source projects
could be very impactful for your career
here are two examples
from reddit users to prove that
those aren't directly related to network
administration but
they are meant to prove a point question
number 46
tell me about the biggest mistake you've
made
the interviewer wants to see if you are
willing to embrace the fact that we're
all fallible
be very open and say that you've made
mistakes but
they have helped you learn a lot and
progress in life
try to mention a technical mistake in
your career instead of a behavioral
mistake
for example you can say that my biggest
mistake was to unplug a server that was
running dhcp
because of this mistake hundreds of
people were not able to access the
network for
almost 50 minutes question number 47
what technical news sources do you check
daily
the interviewer wants to gauge your
passion for networking
just mention your favorite sources a
good example could be the cisco
networking blog
question number 48 tell me about an
instance where your team
client or boss disagreed with you how
did you resolve this situation
this is a very common question asked to
check your attitude towards disagreement
every company wants a person who is open
to disagreements and debate
this question could be approached in a
variety of ways
you can talk about a specific instance
from your career or life
or make up a situation if you have no
experience at all
to prove that you are a good listener
open communicator
and know how to analyze the situation
question number 49
a network administrator is measuring the
transfer of bits across the company
backbone for a
very important application the
administrator notices that the network
throughput is lower than the bandwidth
expected
can you tell which factors could
influence the differences in throughput
some factors responsible could be the
amount of traffic that is currently
crossing the network
the type of traffic that is crossing the
network and the latency that is created
by the number of network devices that
the data is crossing
question number 50 how many hosts are
addressable on a network that has a mask
of 255.255
6. thanks for watching check out the
video on the right
for more information to help you develop
your i.t career
you
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