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Exam 200-310 topic 2 question 162 discussion

Actual exam question from Cisco's 200-310
Question #: 162
Topic #: 2
[All 200-310 Questions]

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You administer the network shown above. RouterA and RouterB are configured to use EIGRP. Automatic summarization is enabled.
What network or networks will RouterA advertise to RouterB?

  • A. 172.16.0.0/16
  • B. 172.16.0.0/22
  • C. 172.16.0.0/23 and 172.16.3.0/24
  • D. 172.16.0.0/24, 172.16.1.0/24, and 172.16.3.0/24
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Suggested Answer: A 🗳️
Section: Addressing and Routing Protocols in an Existing Network Explanation

RouterA will advertise the 172.16.0.0/16 network to RouterB. When the auto-summary command has been used to enable automatic summarization on a router,
Enhanced Interior Gateway Routing Protocol (EIGRP) automatically summarizes networks on classful boundaries. Summarization minimizes the size of routing tables and advertisements and reduces a router's processor and memory requirements. Summarization is also useful in limiting the scope of EIGRP queries.
The 172.16.0.0/24, 172.16.1.0/24, and 172.16.3.0/24 networks in this scenario use Class B addresses. Therefore, these network ranges are summarized to the
Class B boundary, which is /16. Subnetting a contiguous address range in structured, hierarchical fashion enables routers to maintain smaller routing tables and eases administrative burden when troubleshooting. Conversely, a discontiguous IP version 4 (IPv4) addressing scheme can cause routing tables to bloat because the subnets cannot be summarized.
To disable automatic summarization in an EIGRP configuration, you should issue the no auto-summary command. The no auto-summary command enables
EIGRP to advertise the actual networks, not the classful summary. You should use the no auto-summary command when a classful network is divided and portions of the same classful network exist in different parts of the network topology. If you were to issue the no auto-summary command on RouterA, RouterA would advertise the individual network ranges and subnet mask information to RouterB.
You can issue the ip summary-address eigrp command to enable manual summarization. Manual summarization is configured on a per-interface basis. The syntax of the ip summary-address eigrp command is ip summary-address eigrp as number address mask, where as-number is the EIGRP autonomous system
(AS) number, address is the summary address, and mask is the subnet mask in dotted decimal notation.
Reference:
Cisco: Cisco IOS IP Routing: EIGRP Command Reference: auto-summary (EIGRP)

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Monnnn
5 years, 5 months ago
B should be the answer
upvoted 1 times
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