CCNA INTERVIEW QUESTIONS AND ANSWERS
The following CCNA interview questions and answers are a preview from the below book
Question
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.
Explanation
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
How many collision domains are available respectively on 5 port and 8 port hub.
Explanation
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
How many collision domains are available on switch, which has three vlans and 24 ports.
Explanation
On a switch, every port is a collision domain. So on a 24 port switch, there are 24 collision domains.
Question
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.
Explanation
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
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.
Explanation
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 internetwork communication.
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Question
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.
Question
How many vlans can a switch port be a member of, if the port is configured as an access port.
Explanation
A port can only be a member of one vlan, when configured as an access port.
Question
Two RIP routers are configured on a point to point link. One of the RIP routers is behind a firewall. Which port on the firewall needs to be opened for RIP communication to be successful.
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Explanation
RIP messages between RIP enabled routers communicate on UDP port 520. So the port, UDP 520 should be opened on the firewall.
Question
A router is configured with RIP and OSPF routing protocols. It has learnt a path to a specific network through both the protocols. Which path would a packet bound to the network take and why.
Explanation
The path, with the lower administrative distance would be taken by the packet. OSPF has a lower administrative distance (110) than RIP (120). So the path learnt by OSPF would be taken by the packet to reach the destination.
Question 36
What is the Spanning Tree Protocol used for
Explanation
Spanning tree protocol is used to prevent looping of frames. Unlike IP, which has a TTL value field in the packet which is decremented every time the packet passes through a router and is dropped once the value reaches 0, the frame does not have any similar field. So if a scenario arises where a frame is looping in a switched environment, the frame would not automatically time out. The spanning tree protocol is used for preventing the looping.