Cisco Interconnecting Cisco Networking Devices Part 1 (ICND1 v3.0)
Question No: 141 – (Topic 4)
The ip helper-address command does what?
assigns an IP address to a host
resolves an IP address from a DNS server
relays a DHCP request across networks
resolves an IP address overlapping issue
When the DHCP client sends the DHCP request packet, it doesn’t have an IP address. So it uses the all-zeroes address, 0.0.0.0, as the IP source address. And it doesn’t know how to reach the DHCP server, so it uses a general broadcast address, 255.255.255.255, for the destination.
So the router must replace the source address with its own IP address, for the interface that received the request. And it replaces the destination address with the address specified in the ip helper-address command. The client device’s MAC address is included in the payload of the original DHCP request packet, so the router doesn’t need to do anything to ensure that the server receives this information. The router then relays the DHCP request to the DHCP server.
Question No: 142 DRAG DROP – (Topic 4)
Move the protocol or service on the left to a situation on the right where it would be used. (Not all options are used.)
Question No: 143 DRAG DROP – (Topic 4)
Various protocols are listed on the left. On the right are applications for the use of those protocols. Drag the protocol on the left to an associated function for that protocol on the right. (Not all options are used.)
Question No: 144 – (Topic 4)
Refer to the exhibit.
A company wants to use NAT in the network shown. Which commands will apply the NAT configuration to the proper interfaces? (Choose two.)
R1(config)# interface serial0/1 R1(config-if)# ip nat inside
R1(config)# interface serial0/1 R1(config-if)# ip nat outside
R1(config)# interface fastethernet0/0 R1(config-if)# ip nat inside
R1(config)# interface fastethernet0/0 R1(config-if)# ip nat outside
R1(config)# interface serial0/1
R1(config-if)# ip nat outside source pool 126.96.36.199 255.255.255.252
R1(config)# interface fastethernet0/0
R1(config-if)# ip nat inside source 10.10.0.0 255.255.255.0
Answer: B,C Explanation:
For NAT, you need to define which interfaces are inside and which are outside. The outside interface is the one that connects to the external network, and the one that will be used for translating addresses. The inside interface is for the internal network, and defines the network IP addresses that will get translated to the one specified in the outside network.
Question No: 145 – (Topic 4)
What is the best practice when assigning IP addresses in a small office of six hosts?
Use a DHCP server that is located at the headquarters.
Use a DHCP server that is located at the branch office.
Assign the addresses by using the local CDP protocol.
Assign the addresses statically on each node.
Answer: D Explanation:
Its best to use static addressing scheme where the number of systems is manageable rather than using a dynamic method such as DHCP as it is easy to operate and manage.
Question No: 146 – (Topic 4)
A network administrator cannot connect to a remote router by using SSH. Part of the show interfaces command is shown.
Serial0/1/0 is up, line protocol is down
At which OSI layer should the administrator begin troubleshooting?
Answer: B Explanation:
I think the indication here is quot;Serial 0 is up, line protocol is downquot;. What causes this indication? Correct me if I am wrong. When you have this indication, a cable unplugged is not a correct answer. If you check the output of your quot;show interface serial 0quot; command again, you should notice it as quot;Serial 0 is down, line protocol is down. Under the quot;show ip int briefquot; you should see status = down and protocol = down as opposed to up, down.
Because you disconnected the cable, layer 1 will go down, which is indicated by the serial 0 down status. The line protocol status is for layer 2. So, a cable unplugged is not a correct answer to quot;Serial 0 is up, line protocol is downquot;. Up/down means that the physical layer is OK, but there is a problem with the data link link (line protocol).
Question No: 147 – (Topic 4)
When configuring NAT, the Internet interface is considered to be what?
Answer: D Explanation:
The first step to deploy NAT is to define NAT inside and outside interfaces. You may find it easiest to define your internal network as inside, and the external network as outside.
However, the terms internal and external are subject to arbitration as well. This figure shows an example of this.
Reference: http://www.cisco.com/c/en/us/support/docs/ip/network-address-translation- nat/13772-12.html#topic2
Question No: 148 – (Topic 4)
Which of the following statements are TRUE regarding Cisco access lists? (Choose two.)
In an inbound access list, packets are filtered as they enter an interface.
In an inbound access list, packets are filtered before they exit an interface.
Extended access lists are used to filter protocol-specific packets.
You must specify a deny statement at the end of each access list to filter unwanted traffic.
When a line is added to an existing access list, it is inserted at the beginning of the access list.
Answer: A,C Explanation:
In an inbound access list, packets are filtered as they enter an interface. Extended access lists are used to filter protocol specific packets. Access lists can be used in a variety of situations when the router needs to be given guidelines for decision-making. These situations include:
Filtering traffic as it passes through the router To control access to the VTY lines (Telnet)
To identify quot;interestingquot; traffic to invoke Demand Dial Routing (DDR) calls To filter and control routing updates from one router to another
There are two types of access lists, standard and extended. Standard access lists are applied as close to the destination as possible (outbound), and can only base their filtering criteria on the source IP address. The number used while creating an access list specifies the type of access list created. The range used for standard access lists is 1 to 99 and 1300 to 1999. Extended access lists are applied as close to the source as possible (inbound), and can base their filtering criteria on the source or destination IP address, or on the specific protocol being used. The range used for extended access lists is 100 to 199 and 2000 to 2699.
Other features of access lists include:
Inbound access lists are processed before the packet is routed.
Outbound access lists are processed after the packet has been routed to an exit interface. An quot;implicit denyquot; is at the bottom of every access list, which means that if a packet has not matched any preceding access list condition, it will be filtered (dropped).
Access lists require at least one permit statement, or all packets will be filtered (dropped). One access list may be configured per direction for each Layer 3 protocol configured on an interface The option stating that in an inbound access list, packets are filtered before they exit an interface is incorrect.
Packets are filtered as they exit an interface when using an outbound access list.
The option stating that a deny statement must be specified at the end of each access list in order to filter unwanted traffic is incorrect. There is an implicit deny at the bottom of every access list.
When a line is added to an existing access list, it is not inserted at the beginning of the access list. It is inserted at the end. This should be taken into consideration. For example, given the following access list, executing the command access-list 110 deny tcp 192.168.5.0 0.0.0.255 any eq www would have NO effect on the packets being filtered because it would be inserted at the end of the list, AFTER the line that allows all traffic.
access-list 110 permit ip host 192.168.5.1 any
access-list 110 deny icmp 192.168.5.0 0.0.0.255 any echo access-list 110 permit any any
Question No: 149 – (Topic 4)
How many addresses will be available for dynamic NAT translation when a router is configured with the following commands?
Router(config)#ip nat pool TAME 188.8.131.52 184.108.40.206 netmask 255.255.255.224
Router(config)#ip nat inside source list 9 pool TAME
Answer: B Explanation:
220.127.116.11 to 18.104.22.168 provides for 8 addresses.
Question No: 150 – (Topic 4)
In the configuration of NAT, what does the keyword overload signify?
When bandwidth is insufficient, some hosts will not be allowed to access network translation.
The pool of IP addresses has been exhausted.
Multiple internal hosts will use one IP address to access external network resources.
If the number of available IP addresses is exceeded, excess traffic will use the specified address pool.
The keyword overload used in the ip nat inside source list 1 pool ovrld overload example command allows NAT to translate multiple inside devices to the single address in the pool.
The types of NAT include:
Static address translation (static NAT)-Allows one-to-one mapping between local and global addresses.
Dynamic address translation (dynamic NAT)-Maps unregistered IP addresses to registered IP addresses from a pool of registered IP addresses.
Overloading-Maps multiple unregistered IP addresses to a single registered IP address (many to one) using different ports. This method is also known as Port Address Translation (PAT). By using overloading, thousands of users can be connected to the Internet by using only one real global IP address.
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