Network Support Engineer Interview Questions

 

The questions and answers are from the ebook 250+ Network Engineer Interview Questions and answers

 

A PC is connected to a 10/100 Mbps hub. The cable used is Ethernet Cat 5e. Which of the following statements are true about the effective communication between the hub and the PC?

a) Both Half and full duplex
b) Full duplex only
c) Half duplex only
d) Either half or full duplex

Correct answer: C

Explanation:

Hubs can work only in half duplex mode. So the effective communication between the hub and the PC would be half duplex.

A PC is directly connected to an Ethernet routers LAN interface. The IP address of the PC is 192.168.1.1/24 and the IP address of the LAN interface of the router is 192.168.2.1/24. If the PC pings the IP address 192.168.2.1 will a response be received back from the router?

Note: The IP address of the default gateway is not configured on the PC.

a) A response will be received because both are directly connected
b) A response will be received if a cross over cable is used to connect the PC directly to the routers interface.
c) A response will not be received from the router.
d) A response will be received if the default gateway of the PC is set as 192.168.2.1 (Routers interface)

Correct answer:

Explanation:

The routers IP address is on a different network and a default gateway is not configured on the PC. This would cause the PC to drop packets destined for another network on itself. So the router would not receive the packet or send a response.

3 switches SW1, SW2 and SW3 are interconnected and STP deployed on the switches. PC1 is on SW1, PC2 is on SW2 and PC3 is on SW3. All the PC’s are configured with IP address belonging to the network address of 192.168.1.0/24. PC1 triggers ARP request to find the mac-address of PC3. Will the ARP packet reach PC3?

a) PC3 will receive the ARP packet and a response will be send back to the PC1
b)Because STP is enabled ARP packets will not cross Layer 2 infrastructure
c)ARP packet will not cross SW1
d)PC3 is on a different switch. So ARP will not be triggered by PC1

Correct answer: A

 

The questions and answers are from the ebook 250+ Network Engineer Interview Questions and answers

 

Explanation:

All the PC’s are on the same network address. The PC’s are on 3 switches which make it one large Layer 2 broadcast domain. So an ARP request which is a layer 2 broadcast frame will be received on all the ports on all the switches and correspondingly the PC’s. So PC 3 will receive the ARP request and an ARP response sends to PC1.

A network administrator has been asked to deploy a DHCP server on the network to migrate from static to dynamic IP address setting on users. After the deployment the users started to complain about unavailability of internet. What could be the possible reason?

a) The DHCP Servers domain name would not have  been registered on the network
b) DHCP Server created a broadcast storm which made the internet unavailable to the users
c) DNS Server IP address was not configured as a DHCP server options field.
d) A route from the DHCP server was not configured to communicate with the internet router

Correct answer: C

Explanation:
DNS server IP address has to be configured on the clients TCP/IP adapter setting for resolving URL’s to IP address. When migrating from static to dynamic IP address, the DNS IP address information has to be configured as options in DHCP Server such that it would be provided as part of the dhcp address lease and updated along with the dhcp assigned IP address on the TCP/IP adapter settings of the users PC.

A home user uses a Wifi internet router for accessing internet. The wifi router has one public IP address for internet and the LAN private IP address of the user and the router is 192.168.1.2/24 and 192.168.1.1/24 respectively. How many more users (IP address) can be available on the LAN?

a) 253
b) 251
c) None of these
d) 250

Correct answer: C

Explanation:
The usable hosts on the LAN network would be 254 deducting the network and broadcast address  (192.168.1.0 – network address) and (192.168.1.255 – broadcast address) . Out of this two are already in use by the user and the router. So the remaining available number of IP addresses would be 252.

A network administrator has been assigned a task of setting up two networks 192.168.1.0/24 and 192.168.2.0/24. He has two Layer 2 switches for connecting the users. What is the most economical way to setup communication between the networks?

a) Configure two network cards on a PC and make the PC as gateway for the networks
b) Purchase and configure a router as the gateway for networks
c) Do not use the second switch. Connect all the users on one switch and make the switch as the gateway.
d) Add the following commands on every client PC to route packets to respective networks

route add 192.168.1.0
route add 192.168.2.0

Correct answer: A

Explanation:

The most economical way would be to use two network cards on the PC.

Thomas spoofs the mac-address of his PC to that of George’s PC. He then attempts an ARP request on the LAN network to find the mac-address of the gateway. What will be the sender mac-address value in the ARP protocol header?

a) mac-address of George
b) mac-address of Thomas
c) ARP request will not be triggered with a spoofed mac-address
d) The gateways mac-address

Correct answer: A

Explanation:
The sender mac-address inside the ARP protocol header would be the mac-address of the device which initiates the ARP request. In this case, Thomas has edited his mac-address and the current value is that of George’s mac-address. This would cause the sender mac-address inside the ARP protocol header to be reflected to that of George’s mac-address.

The questions and answers are from the ebook 250+ Network Engineer Interview Questions and answers