Exam: 200-301: Cisco Certified Network Associate (CCNA) 0 Likes
An engineer must update the configuration on two PCs in two different (CCNA 200-301)
An engineer must update the configuration on two PCs in two different subnets to communicate locally with each other. One PC is configured with IP address 192.168.25.128/25 and the other with 192.168.25.100/25.
Which network mask must the engineer configure on both PCs to enable the communication?
A. 255.255.255.248
B. 255.255.255.224
C. 255.255.255.0
D. 255.255.255.252
Solution
Correct answer: C. 255.255.255.0.
1. Understand the current configuration:
The IP addresses of the two PCs are:
PC1: 192.168.25.128/25
PC2: 192.168.25.100/25
The /25 subnet mask translates to 255.255.255.128.
This subnet mask creates two subnets within the 192.168.25.0/24 range:
Subnet 1: 192.168.25.0 - 192.168.25.127
Subnet 2: 192.168.25.128 - 192.168.25.255
2. Check subnet allocation:
PC1 (192.168.25.128) is in Subnet 2: 192.168.25.128 - 192.168.25.255.
PC2 (192.168.25.100) is in Subnet 1: 192.168.25.0 - 192.168.25.127.
These PCs are not in the same subnet, so they cannot communicate directly without a router.
3. Modify the subnet mask:
To allow both PCs to communicate directly, they must be placed in the same subnet. This can be achieved by using a larger subnet mask that combines the two existing subnets.
Subnet mask calculation:
A /24 subnet mask (255.255.255.0) would combine 192.168.25.0 - 192.168.25.255 into a single subnet.
With this mask:
The network range would be 192.168.25.0 - 192.168.25.255.
Both PC1 (192.168.25.128) and PC2 (192.168.25.100) fall within this range.
4. Answer:
The engineer must configure the subnet mask as 255.255.255.0 on both PCs to enable direct communication.
Category: IP Connectivity