Research-Aptitude
October 19, 2023GATE 1989
October 19, 2023Subnetting
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Question 3
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Consider the following routing table at an IP router:
For each IP address in Group I identify the correct choice of the next hop from Group II using the entries from the routing table above.
Group I Group II
(i) 128.96.171.92 (a) Interface 0
(ii) 128.96.167.151 (b) Interface 1
(iii) 128.96.163.121 (c) R2
(iv) 128.96.165.121 (d) R3
(e) R4
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i-a, ii-c, iii-e, iv-d
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i-a, ii-d, iii-b, iv-e
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i-b, ii-c, iii-d, iv-e
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i-b, ii-c, iii-e, iv-d
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Question 3 Explanation:
Do the AND operation of group I IP address with Netmask and compare the result with network number. if it match with network number, forward packet through that interface.
Ex: 128.96.167.151 AND 255.255.254.0 = 128.96.166.0
Therefore packet will forward through R2.
Ex: 128.96.167.151 AND 255.255.254.0 = 128.96.166.0
Therefore packet will forward through R2.
Correct Answer: A
Question 3 Explanation:
Do the AND operation of group I IP address with Netmask and compare the result with network number. if it match with network number, forward packet through that interface.
Ex: 128.96.167.151 AND 255.255.254.0 = 128.96.166.0
Therefore packet will forward through R2.
Ex: 128.96.167.151 AND 255.255.254.0 = 128.96.166.0
Therefore packet will forward through R2.