A branch of a company recently switched to a new ISP. The network engineer was given a new IP range to assign. The ISP assigned 196.26.4.0/26, and the branch gateway router now has the following configurations on the interface that peers to the ISP:
The network engineer observes that all users have lost Internet connectivity. Which of the following describes the issue?
The issue arises from an incorrect gateway configuration. The assigned IP range is 196.26.4.0/26, where the correct subnet mask should be 255.255.255.192. The provided IP address (196.26.4.30) sits within this range. However, the configured gateway (196.24.4.1) falls outside the 196.26.4.0/26 subnet, making it impossible for devices within this network to route traffic through the gateway. Therefore, the correct gateway should be an address within the 196.26.4.0/26 subnet.
Gateway is the correct answer. XX.XX.4.1 and XX.XX.4.30 will still be in the subnet when the mask is set to 255.255.255.224 (/27)
to add to this you can see that the gateway is xx.24.xx.xx as opposed to the IPs being on xx.26.xx.xx
And some of claim that the user can use /27 subnet mask, yes, that can be happened but check the question. It states "The network engineer observes that all users have lost Internet connectivity.". All peer's IP configuration is fine with /27 but it can't explain why all users have lost their internet connections.
That is because the range 196.26.4.0 - 196.26.4.31 which is in /27 is also in the range of 192.168.4.0/26 (which is 192.168.4.0 - 192.168.4.63). When the subnet mask is applied it will think the gateway is directly connected and will send the arp request to the gateway if the gateway was set correct.
The question says 196.26.4.0/26 not 196.26.4.0/27. Therefore, the Subnet Mask is wrong and it won´t work as the /26 was given by the ISP and it can´t be modified.
Totally agree with you. The Subnet mask is wrong, they need be 255.255.255.192 for /26
I corrected myself, the gateway configuration is incorrect.
Incorrect Subnet Mask was configured. The correct subnet mask is 255.255.255.192
Incorrect. You can use /27 even though ISP gave you a /26. The gateway however is not in the network at all
Both an incorrect subnet mask and an incorrect default gateway can cause loss of Internet connectivity. However, given the information provided: - The subnet mask is set to 255.255.255.224, but it should be 255.255.255.192 for a /26 network. This incorrect subnet mask could cause issues with routing and connectivity within the local network. - The gateway IP address is set to 196.24.4.1, which is not in the same subnet as the IP address of the interface (196.26.4.30). This could prevent the router from correctly routing traffic to and from the Internet. It's hard to definitively say which is the "main" cause without more information, as both could potentially lead to a loss of Internet connectivity. However, typically, an incorrect default gateway would more directly lead to a loss of Internet connectivity, as the default gateway is responsible for routing traffic between the local network and the Internet. So if forced to choose one, I would lean towards **B. The incorrect gateway was configured** as being the main cause.
This is an excellent explanation, thank you very much.
I took the exam last week (on March 21, 2024) and I answered A (incorrect subnet mask). I scored 861/900. It is not answer B (incorrect gateway), because the gateway mentioned in the question was: 196.26.4.1
did you just study this to pass? or did you also do self studying to get that high of a score?
Going with gateway for now. I'm guessing that for this question, even if the subnet mask was incorrect like it is here, it wouldn't really explain the loss of internet connectivity for all users. The /26 subnet assigned by the ISP would mean that the router should use 255.255.255.192 as the subnet and not 255.255.255.224 since it's /27. The incorrect subnet should lead to some routing issues between the router and the ISP, but you might still can get internet connectivity depending on the ISP. An incorrect gateway would flat out stop all internet connectivity since the traffic would have no way to being properly routed. This could just be a typo with the gateway since another comment mentioned that the test had updated the gateway to be a valid IP. If that's the case I'd go with subnet, but for now sticking with gateway.
Really is not an incorrect subnet, because you can use VLSM and you can have an address, with /27 after you have a /26 came from the ISP, but if you look the gateway IP address. 196.24.4.1 and the network address is 196.26.4.0 so the gateway is in a different network.
both the gateway and the subnet mask are incorrect. However, the issue that directly impacts the loss of Internet connectivity for all users is the incorrect gateway configuration.Even if the subnet mask were correct, without the correct gateway, the traffic wouldn't be routed properly to reach the internet. So, while both are issues, the incorrect gateway configuration more accurately describes the immediate cause of the loss of connectivity. Therefore, option B, the incorrect gateway configuration, best describes the issue.
Gateway, second octet is different
Incorrect Subnet is answer /26 means 8.8.8.11000000 255.255.255.192 also /26 gives 64 ip address. ISP and client ip are within the 64 Range
/30 would be ".252" not "224". Subnet Mask Is Incorrect. Google and take a look at the CIDR notation sheet
network segment set by the ISP at their branch is /26 so the subnet mask should be the same as of the ISP and our company network. moreover, the gateway device is not the end device(router) in the company that is also handled by the ISP and of course, the rules are set by the ISP to route our company inquiries and all. (Hope, I able to explain what I want to say English is not my first language) Thanks
I typed whole question and image into BING AI: The issue is with the gateway that was configured. The gateway IP address should be within the same subnet as the IP address of the interface. In this case, the IP address of the interface is 196.26.4.30 and it falls within the 196.26.4.0/26 subnet. However, the gateway IP address 196.24.4.1 does not fall within this subnet. Therefore, the correct answer is B. The incorrect gateway was configured. The gateway should be an IP address from the 196.26.4.0/26 subnet.
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Incorrect Subnet is answer /26 means 8.8.8.11000000 255.255.255.192 also /26 gives 64 ip address. ISP and client ip are within the 64 Range
The correct answer is B. The incorrect gateway was configured. The gateway IP address should be within the same subnet as the IP address of the interface. The subnet for the IP address 196.26.4.30 with subnet mask 255.255.255.224 (/26) is 196.26.4.0 to 196.26.4.63. However, the configured gateway IP address 196.24.4.1 is not within this range. Therefore, the gateway IP address is incorrect and needs to be reconfigured to an IP within the 196.26.4.0/26 subnet.
The gateway router's interface configuration includes the following information: IP address: 196.26.4.30 Subnet mask: 255.255.255.224 Gateway: 196.24.4.1 The subnet mask 255.255.255.224 corresponds to a /27 subnet, not a /26 subnet. Therefore, the correct subnet mask for the assigned IP range 196.26.4.0/26 should be 255.255.255.192, not 255.255.255.224. This misconfiguration prevents the gateway router from properly communicating with devices outside the local network, causing all users to lose Internet connectivity.
Clearly, the gateway is not in the ISP-provided subnet range
The second octet on the gateway is wrong