Home > ICND1 – IP Routing

ICND1 – IP Routing

June 14th, 2017 in ICND1 100-105 Go to comments

Note: The ICND1 exam requires candidates to understand basic knowledge of dynamic routing protocols (RIP, EIGRP, OSPF).

Question 1

Question 2

Explanation

By default, Cisco routers do not forward broadcast address. So what will happen if your PC does not in the same LAN with DHCP Server? Your PC (also a DHCP Client) will broadcast a packet but it is dropped by the router -> Your PC cannot get the IP from DHCP Server. So the “ip helper-address” command enables the DHCP broadcast to be forwarded to the DHCP server. For example, the IP address of your DHCP Server is 10.10.10.254 then we can type in the interface connecting with the DHCP Client (fa0/0 in this case) this command: “ip helper-address 10.10.10.254”.

IP_helper-address.jpg

Note: When a client boots up for the first time, it transmits a DHCPDISCOVER message on its local physical subnet. Because the client has no way of knowing the subnet to which it belongs, the DHCPDISCOVER is an all-subnets broadcast (destination IP address of 255.255.255.255, which is a layer 3 broadcast address). The client does not have a configured IP address, so the source IP address of 0.0.0.0 is used.

Question 3

Explanation

Routers do not look to the destination MAC address to forward packet. It will find the next destination MAC address itself to replace the old destination MAC address of the received packet.

Hubs do not care about MAC addresses, it just flood the frames out of all its port except the port that sent it.

Therefore only three switches in the exhibit above use destination MAC address to determine the next hops.

Question 4

Explanation

The destination MAC address at point A must be the MAC address of the interface fa0/0 of Toronto router -> E is correct.

Question 5

Explanation

The simple syntax of static route:

ip route destination-network-address subnet-mask {next-hop-IP-address | exit-interface}
+ destination-network-address: destination network address of the remote network
+ subnet mask: subnet mask of the destination network
+ next-hop-IP-address: the IP address of the receiving interface on the next-hop router
+ exit-interface: the local interface of this router where the packets will go out

Therefore the purpose of this command is to send any packets with destination IP address in the range of 192.168.100.160/27 subnet to 192.168.10.2. In fact, answer C is a bit weird when saying “host 192.168.100.160” because 192.168.100.160 is the network address in this case and it cannot be assigned to a host. But answer C is the most suitable answer for this question.

Question 6

Question 7

Explanation

After receiving a packet, the router will keep the source and destination IP addresses while change the source MAC address (to the MAC address of its outgoing interface) and the destination MAC address (to the MAC address of the next-hop interface). Therefore when the packet reaches host B, the source MAC address must be the MAC address of the outgoing interface of R1.

Question 8

Explanation

Host A knows the IP address of Host B but it does not know the MAC address of host B, so it have to create an ARP Request (which is a broadcast frame) to ask for the MAC address of host B. When Router1 receives this ARP Request, it answers with its own MAC address.

Question 9

Question 10

Explanation

Along the routing path, the source and destination IP address will not change so the source IP will always be 10.1.1.16.

Comments (55) Comments
  1. Jack
    December 13th, 2013

    Question 5, answer C.
    It should not read host. That IP address is a subnet ID and cannot be assigned to a host.
    Host should be replaced with the word subnet, or network.

  2. testingsoon
    December 19th, 2013

    If someone sees this, why is the answer to question 9, B? Why can’t it be D, enable VLAN trunking? THanks

  3. Networker
    December 22nd, 2013

    @testingsoon

    VLAN trunking does not route between VLANs, it only passes the traffic between switches on which the trunk is set up.

    The VLANs are each on their own subnets, and a layer 2 switch cannot route between different subnets. Thus, you need a router to route the traffic between the two

  4. kjk
    January 27th, 2014

    Reference #9, this is what Cisco calls ‘Router on a stick’….setting up a router just to route between different VLANS on a switch.

  5. CCENT Someday
    January 31st, 2014

    Anyone,

    I plan on taking exam next week. What other sims/labs did you get besides the OSPF 6 router?

    Thanks in Advance!

  6. Mason
    February 6th, 2014

    Hi 9tut,
    I think Q8 answer should be C. 00-17-94-61-18-b0, not E. ff-ff-ff-ff-ff-ff. Am i right?

  7. 9tutq
    February 7th, 2014

    @Mason: Q8 answer is E because Host A knows the IP address of Host B but it does not know the MAC address of host B, so it have to create an ARP Request (which is a broadcast frame: FF-FF-FF-FF-FF-FF) to ask for the MAC address of host B first.

  8. Mason
    February 10th, 2014

    @ 9tut
    I do appreciate for your great job.
    we should keep this site up even with a small donation.

  9. CCENT_PREP
    February 11th, 2014

    @testingsoon

    The answer is not D because the switch used in this exhibit is not a Layer 3 switch. I think Cisco uses a different image for Layer 3 switch. And only Layer 3 switches have routing capability.

  10. Kim
    February 12th, 2014

    i am preparing my ICND1 exam, the explanation of question 2; the ip helper-address will be on conf mode or the interface mode?

  11. as20140202
    February 14th, 2014

    ——————————–
    testingsoon
    December 19th, 2013

    If someone sees this, why is the answer to question 9, B? Why can’t it be D, enable VLAN trunking? THanks
    ——————————–
    Trunking is used in between switches.
    We would need routing between 2 vlans, so 2 seperate ip subnets too.
    1 way to achieve this is a router (Router On A Stick in this situation)
    second way is to implement L3 intervlan routing, by using L3 capable switch.
    Am i wrong? 🙂

  12. Eddie
    February 19th, 2014

    Q9 is correct, I just tried it via packet tracer. 192.168.2.x and 192.168.3.x are on different subnets so without routing they should not be able to talk. The trunking may work on a layer 3 switch but the one in the picture is a layer 2 device and layer 2 is only concerned with physical addressing and you would need logical support to get this to work. Given the answers supplied I do believe the correct answer would be the Router on a Stick approach.

    I test in a couple days and I feel very good given these questions. I hope I finally knock this out!

  13. DCMainiac
    February 21st, 2014

    Shouldnt question 8 be C. According to the diagram it knows its destination IP address and not its MAC Address, so it will forward it to its default gateway router 1. Once it gets to R1, R1 identifies it isnt its IP address, then replaces its mac then forwards to R2

  14. fructal
    February 28th, 2014

    DCMainiac I think it goes like this: PC looks at dest. IP and it’s subnet mask, realizes other PC is on a different subnet – then it ARPs for MAC of its default gw. So, in reality it doesn’t ARP for host B MAC but for its def gw MAC.

  15. Konan
    March 3rd, 2014

    @DCMainiac,
    if host sends ARP request for getting MAC of default-gateway it means that in its arp-cache MAC of gateway doesnt exist.And host uses broadcast L2 address as destination:
    arp request:source IP:IP of hostA,destination IP:IP of gateway,source MAC:MAC of hostA,destination MAC:FF:FF:FF:FF:FF:FF.

  16. Rafaqat
    April 19th, 2014

    Hello Every one

    Please send me vce file to open dump on my email rafaqat_edu@yahoo.com

  17. Mustafa
    April 22nd, 2014

    Either router on a stick or L3 switch should be used to route the traffic between two vlans period, without routing mechanism you have no communication between the vlans each vlan is a separate broadcasting area this is how vlans works ;).

  18. fez
    April 24th, 2014

    Passed my 100-101 exam today and question 2,4,5,7,9 were there.. all the best

  19. Manohar Tn
    May 16th, 2014

    Got 986/1000 Marks, {5/16/2014} 50 Questions, Ospf Sim, Security simlet, and Router and switch Simlet Was also there…..All questions From 9tut. and Examcollections…..Now Heading For Icnd2 And Blogging…..

    For Any Help.
    Manohar Tn
    Website: http://www.techlinko.com
    G+ : https://plus.google.com/u/0/+ManoharTN9/

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    May 29th, 2014

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  21. AK
    July 18th, 2014

    Please share more if you’ve different questions and you took 100-101 recently. Thanks

  22. JamesK
    September 17th, 2014

    Q1 – In this day & age, with mobile devices such as laptop computers so prevalent, I don’t think static addresses are appropriate any more. If you want fixed addresses for users, just configure the DHCP server to do that. Also, with today’s routers, a DHCP server is almost always available. With IPv6, this issue doesn’t even arise, as there are 2 methods, MAC address and random number, for setting an address, though DHCP and static configuration are still available.

  23. JamesK
    September 17th, 2014

    Q8 – “Host A knows the IP address of Host B but it does not know the MAC address of host B, so it have to create an ARP Request (which is a broadcast frame) to ask for the MAC address of host B. When Router1 receives this ARP Request, it answers with its own MAC address.”

    That is absolute nonsense. Host A will look at the destination address and compare it with the network it’s on. If it determines the address is not on the local network, it will send the packet to the router. It will first do an ARP request for the router’s MAC address, if it doesn’t already know it. The router couldn’t possibly send it’s MAC address to that request, because that request would never happen.

  24. Anonymous
    September 19th, 2014

    @JamesK: exactly…. I thought nobody was going to mention that.

    When host A sends a broadcast to get the MAC address for host B, the router would drop that packet imediately. Which host A would never do because it knows it is on another network.

    Therefor Host A will send the broadcast to get the MAC address of the router. Then finally Host A will send the packet to host B with the Destination MAC address of the router.

  25. Anonymous
    September 26th, 2014

    qs 8 answer should be C ?

  26. JamesK
    September 26th, 2014

    @Anonymous
    No, the answer, despite the nonsense explanation is E. Arp requests are broadcasts, so they go to MAC address ff-ff-ff-ff-ff-ff. Since B is not on the same network as A, A forwards the packet to the router. However, if A doesn’t know the MAC for router 1, it will do an arp request for the router’s MAC. The router will never respond to a arp for B.

  27. JJ
    October 21st, 2014

    Will there be any questions related to ACL and IPv6 on ICND1 exam? answers appreciated

  28. Vahid
    October 21st, 2014

    Question 5
    .160 is the network address, not host address. That IP address is a subnet ID and cannot be assigned to a host. Host should be replaced with the word subnet, or network or there is no correct answer.

  29. Anonymous
    November 6th, 2014

    The answer to question 8 is C due to proxy arp being enable by default on CISCO routers…

  30. Anonymous
    November 6th, 2014

    Whoops, sorry, it would help if I read the question carefully. I read it as what would the router use, not Host A for the initial request.

  31. Yahia Tariq
    November 22nd, 2014

    Questions 1-2-6-9 were in exam on 20/11/2014, more than 45 questions were from 9tut !

  32. Abdel
    December 20th, 2014

    testingsoon:
    If someone sees this, why is the answer to question 9, B? Why can’t it be D, enable VLAN trunking? THanks.

    It is B because a a trunk can only be setup between switch to switch or switch to router.
    In this scenarios, we will use a router with two subinterfaces (one for each vlan) and run a trunk port from the router to the switch. The router will receive traffic from vlan 2 and send it back down the trunk to vlan3 and vice versa.

  33. Techgique
    January 26th, 2015

    @ Vahid, and @9tut Although the default route makes sense that anything destined for that subnet should go to the next hop address, Vahid is correct in the syntax and that shouldn’t say “Host” on the answer to Q5, rather it should say “…packets destined for network…”.

  34. John
    January 27th, 2015

    regarding Q4 I don’t quite agree with the answer, it says in the question what the MAC address will be at this point A, which means the packet hasn’t reached the fa0/0 port yet, so it should still be the host’s MAC not the fa0/0, the MAC address only change when it go through the router, is that correct? many thanks!

  35. Techgique
    February 3rd, 2015

    @John, the source MAC address will indeed be the host, but the question asks for the destination MAC address, which will be the Fa0/0 port of the Toronto router

  36. Ahmed
    March 28th, 2015

    q1,2,8,9 in icnd1 exam

  37. Anonymous
    April 15th, 2015

    hi guys Q 2,6 and 9 were in the exam

  38. G-10
    April 26th, 2015

    Q 1,2,4,5 (answer C),6,8,9 in exam

  39. Atlanta
    June 5th, 2015

    HI! Could someone PLEASE send me the latest ICND1 dumps? THANKS evansj51@yahoo.com

  40. 9tut
    July 13th, 2015

    @all: We had to move all the questions and answers out of 9tut. We can only keep the explanation. You can download the questions and answers at: https://mega.co.nz/#!oIdESYbD!yyu33vygrfKPy4rcmcbV6qW2fxINNoTokuDM3CjA_og

  41. chicken
    September 7th, 2015

    Where are the questions? I see the explanation, but not the actual code question

  42. chicken
    September 7th, 2015

    Where are the questions? I see the explanation, but not the actual questionion

  43. Anonymous
    September 16th, 2015

    Hi 9tut are these still up todate

  44. jay
    January 21st, 2016

    Hi 9tut are these still up todate

  45. Tabo
    June 17th, 2016

    Is there is any ACL question in ICND-1 ? please comment

  46. Anonymous
    June 25th, 2016

    I’m also curious if there are any ACL related questions in the first exam?

  47. mooooooo111
    December 21st, 2016

    Send me link to download packet tracer for free.

  48. Noname
    January 14th, 2017

    Question: 10

    Wouldn’t the source IP address changed if NAT is involved? As it leaves Kiev, the Kiev router would replace the source IP and please it’s own IP address which is 10.1.0.6.

    Please help 🙁

  49. icnd 1 exam pro
    February 7th, 2017

    exhibits of the questions are not showing, admin please fix this , thanks

  50. lestat
    April 5th, 2017

    Hi Can you help me with the correct answer for this question, got to different answer, is it A or C?

    After you configure a default route to the Internet on a router, the route is missing from the routing table. Which option describes a possible reason for the problem?

    A. The next-hop address is unreachable.
    B. The default route was configured on a passive interface.
    C. Dynamic routing is disabled.
    D. Cisco Discovery Protocol is disabled on the interface used to reach the next hop.

  51. CRoss
    May 9th, 2017

    I believe is A @lestat

  52. Shawn
    May 12th, 2017

    Hello every one!
    I can only see the answers and i am not able to see the question part. some one can help please?

  53. jane woken
    May 16th, 2017

    hi guys,
    can someone send me the dumps according the answers of this site for ICND1???? please please please. I really neeeeeeeeeeeeeeeed it. my email address is jane_woken52 at yahoo dot com . It will be big help. Pleeeeeeeeeeeeeeeease .

    my email address is jane_woken52 @ yahoo . com

  54. Dan
    May 19th, 2017

    Unable to see questions, only answers, even on premium.

  55. 9tut
    May 21st, 2017

    @Dan: If your problem still exists, please send an email to support@9tut.net with your username so that we can help you.