# Questions with Explanation

Topics: IP address, Ethernet, Address Resolution Protocol Pages: 80 (31178 words) Published: October 20, 2011
Q1: If an Ethernet port on router was assigned an IP address of 172.16.112.1/20, what is the maximum number of hosts allowed on this subnet? A. 1024 B. 2046 C. 4094 D. 4096 E. 8190 Answer: C Explanation: Given IP address of 172.16.112.1 / 20, subnet mask: 255.255.240.0 max. num of hosts =(( 2^12) -2 ) = 4096-2 = 4094 Q2.:An access list was written with the four statements shown in the graphic. Which single access list statement will combine all four of these statements into a single statements that will have exactly the same effect?

A. access-list 10 permit 172.29.16.0 0.0.0.255 B. access-list 10 permit 172.29.16.0 0.0.1.255 C. access-list 10 permit 172.29.16.0 0.0.3.255 D. access-list 10 permit 172.29.16.0 0.0.15.255 E. access-list 10 permit 172.29.0.0 0.0.255.255 Answer: C Explanation: 172.29.16.0 is an aggregate address for those 4 networks. If you would write all these addresses in binary form and will mark the equal part, than you will see that it is 172.29.16.0. Q3. Refer to the exhibit , what is the most efficient summarization that R1 can use to advertise its networks to R2?

A. 172.1.0.0/22 B. 172.1.0.0/21 C. 172.1.4.0/22 D. 172.1.4.0/24 172.1.5.0/24 172.1.6.0/24 172.1.7.0/24 E. 172.1.4.0/25 172.1.4.128/25 172.1.5.0/24 172.1.6.0/24172.1.7.0/24

Answer : C Explanation:Route Summarization Overview:In large internetworks, hundreds, or even thousands, of network addresses can exist. It is often problematic for routers to maintain this volume of routes in their routing tables. Route summarization (also called route aggregation or supernetting) can reduce the number of routes that a router must maintain, because it is a method of representing a series of network numbers in a single summary address.

For example, in the figure above, router D can either send four routing update entries or summarize the four addresses into a single network number. If router D summarizes the information into asingle network number entry, the following things happen: 1. Bandwidth is saved on the link between routers D and E. 2. Router E needs to maintain only one route and therefore saves memory. 3. Router E also saves CPU resources, because it evaluates packets against fewer entries in its routing table. A summary route is announced by the summarizing router as long as at least one specific route in its routing table matches the summary route. Q4.Which routing protocols can be used within the enterprise network shown in the diagram? (Choose three.)

A. RIP v1 B. RIP v2 C. IGRP D. OSPF E. BGP F. EIGRP

Answer: B, D, F Explanation:In this network there are IP subnets which use variable length subnet masks. RIP V2,OSPF and EIGRP are the interior routing protocols that support VLSM. Q5. Refer to the exhibit. The network shown in the exhibit has just been installed. Host B can access the internet, but it is unable to ping host C. What is the problem with this configuration?

A. Host B should be in VLAN 13 B. The address of host C is incorrect. C. The gateway for host B is in a different subnet than the host is on. D. The switch port that sends VLAN 13 frames from the switch to the router is shut down. E. The switch port connected to the router is incorrectly configured as an access port. Answer: B Explanation: The Fa0/0.13 interface of the router is the subinterface used for VLAN 13. The IP address of this interface is 172.19.13.254, so all devices in VLAN 13 will have their default gateway set to this 172.19.13.254 which means that all devices in VLAN13 need to be in the 172.19.13.0/24 subnet. As can be seen in the output above, Host C is in VLAN 13 but its IP address has been incorrectly configured for the 172.19.14.0/24 subnet. Q6. The user of Host1 wants to ping the DSL modern/router at 192.168.1.254. Based on the Host1 ARP table that is shown in the exhibit, what will Host1 do?

A. send Layer 3 broadcast packets to which the DSL modern/router responds B. send a unicast ARP packet to the DSL modern/router C. send a Layer...