CCNA Interview Questions

The following CCNA interview questions are a preview from the below Ebook.

Question 1

The IP address of a PC is 192.168.1.2/24 and its default gateway is 192.168.1.1/24. The user on the PC pings an IP address which is on a different network (IP address: 192.168.2.2, Default gateway: 192.168.2.1). What would be the destination IP address in the IP header in the ping response packet coming from the IP address 192.168.2.2?

The ping response packet would contain the initiator’s IP address in the destination IP address field in the IP header , which would be 192.168.1.2.

Question 2

What is the use of a subnet mask in the routing table of a router?

The subnet mask is used to identify the network address corresponding to the received IP packets on the router. Assume that an IP packet has arrived with the destination IP address as 192.168.1.5.The route table contains the following entry.
192.168.1.0 255.255.255.0.
192.168.1.5 would be “And ed” with 255.255.255.0 and determined that the destination IP address is a member of the 192.168.1.0 network.

Question 3

Which of the following fields in an ethernet frame would be modified when it moves from port 1 to port 2 of a switch?

-Destination mac-address
-Source mac-address
-Data

When an Ethernet frame is generated, the Destination mac-address would be the receiver’s mac-address and not the switch port’s address. When the frame passes through the port, none of the fields above would be modified.

Question 4

A router has two paths to a network with a static route and dynamic routing protocol. Which path would a packet bound to the network take when it reaches the router?

When there are two paths to the same network, the path with the lower administrative distance would be used for forwarding the packet. The AD (Administrative Distance) of static route is lower than that of dynamic routing protocols. So the path which the static route points to would be taken by the packet.

Question 5

How many collision domains are available respectively on 5 port and 8 port hub?

On a hub, all the ports belong to only one collision domain. So irrespective of the number of ports on the hub, there is only one collision domain on both the hubs.

Question 6

How many collision domains are available on switch which has three vlans and 24 ports?

On a switch, every port is a collision domain. So on a 24 port switch, there are 24 collision domains.

Question 7

PC1 is configured on a port on switch 1, which is a member of VLAN 2. PC2 is connected to a port on switch 2, which is also a member of VLAN 2. Switch 1 and Switch 2 are interconnected with each other. PC1 and PC2 belong to the same network address. Can PC1 ping PC2?

The link between the switches should be configured as a trunk link. This would allow VLAN traffic from one switch to reach the other switch. Once the trunk link is setup, PC1 can ping PC2.

Question 8

On a switch, port 2 and port 3 are configured as members of VLAN 2. PC1 and PC2 are connected to the ports on the switch respectively. The IP address of PC1 is 192.168.1.2/24 and of PC2 is 192.168.2.2/24 respectively. Can PC1 ping PC2?

It can be observed that PC1 and PC2 are residing on different networks. So although they reside on the same VLAN, a router would be required for inter-network communication.

Question 9

Which VLAN protocol can be used to setup VLAN trunking between switches from different manufacturers?
Explanation

802.1Q is a vendor neutral VLAN standard. Protocols like ISL are proprietary to Cisco. So 802.1Q can be used for VLAN trunking between switches from different manufacturers.