Home > Troubleshooting Lab Challenge 1

Troubleshooting Lab Challenge 1

April 19th, 2015 in Lab Challenges Go to comments

Note: We created this lab challenge to help you get some practice with networking problems only. These labs are only for fun and do not appear in the TSHOOT exam. Please let us know if you like this simulator or not so that we can continue making other simulators in the future. Any suggestion, recommendation, error reports are warmly welcomed!

Troubleshooting Lab Challenge 1:

A network engineer has edited their network configuration and now your customer is experiencing network issues. Some reports said that users connected to CLIENT router (R4) cannot reach the services located at SERVER router (R3). They have contacted you to resolve the issues and return the network to full functionality.


To troubleshooting effectively you should understand how this network works. We summarize it as follows:

+ OSPF is running among R1, R2, SW5 and SW6, all are in Area 0
+ R1 and R2 are two DHCP Servers
+ R1 is only responsible for answering DHCP Request from SERVER (R3)
+ R2 is only responsible for answering DHCP Request from CLIENT (R4)
+ Interfaces E0/0 of SERVER and CLIENT is running DHCP to request IP addresses
+ There is an access-list named “edge_security” on SW5 that prevents devices with source IP of 172.16.0.x from accessing the SERVER.

There are 9 tickets waiting for you to resolve. Below are the links to access them:

Ticket 1 Ticket 2 Ticket 3 Ticket 4 Ticket 5
Ticket 6 Ticket 7 Ticket 8 Ticket 9  

Please try your best to solve these tickets!

You can find the solution and explanation for each ticket here.

Comments (50) Comments
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  1. Abdul Nasir
    April 19th, 2015

    it’s just for practice ?

  2. Abdul Nasir
    April 19th, 2015

    or we face in real exam ?

  3. Gaddi
    April 19th, 2015

    Just for Practice. IPs of Server and Client are no OK. one is and second one is 172.16.100.x/24. I think it should be ???

  4. Gaddi
    April 19th, 2015

    Oh. It depends on DHCP, what IP is being lease. Sorry

  5. Julián
    April 19th, 2015


    It seems there is a typo on the diagram. It should be R3 (DHCP Server) rather than R3 (DHCP Client) since R3 is the DHCP server.


  6. networktut
    April 20th, 2015

    @Julián: It is not a typo. R3 is the SERVER for other applications (WEB, FTP, Email…) but it still needs to request IP via DHCP so it is a DHCP Client.

  7. Julián
    April 20th, 2015


    Ok, apologies.


  8. aR@blr
    April 20th, 2015

    Nettut ticket 2 is not having proper ans unable to reach from sw6 to client device ???

  9. networktut
    April 20th, 2015

    @aR@blr: Yes, it is a mistake. Thanks for your detection, we have just updated it!

  10. Hes
    April 20th, 2015

    I checked whole of your Tickets, it seems you are focusing on DHCP like IP-Helper, which is not in real Exam. Am I right ?

  11. networktut
    April 20th, 2015

    @Hes: Yes, this topology focuses on DHCP. Please noticed that we created this lab challenge to help you get some practice with networking problems only. These labs are only for fun and do not appear in the TSHOOT exam.

  12. Grendel
    April 20th, 2015

    Nice one, thanks!

  13. Hes
    April 21st, 2015

    I got it, thanks for everythings.

  14. $@ndyp
    April 21st, 2015

    the first ticket has no answer i tried every ans,but no one is correct , can you tell me the correct anser for ticket 1 ??

  15. Dream
    April 21st, 2015

    Why does every ticket have the same question?

    “Some reports said that users connected to CLIENT router (R4) cannot reach the services located at SERVER router (R3).”

  16. networktut
    April 21st, 2015

    @Dream: Yes, each ticket has a different problem but the same result “sers connected to CLIENT router (R4) cannot reach the services located at SERVER router (R3)”. Your task is to find out where the problem is.

  17. Steven
    April 21st, 2015

    Challenge Ticket#1 Answers:
    A1: SW6
    A2: Port Security
    conf t
    int e0/0
    no swi port-sec
    no swi port-sec mac-add 0000 0000 0001
    no shut

  18. Mike
    April 21st, 2015

    Ticket 7: Client is having same config error like Server, although he works just fine :(

  19. networktut
    April 21st, 2015

    @Mike: It is not a mistake of our simulator. It is a trick!

  20. Mike
    April 21st, 2015


    OK Yes, so parameter: “client-id Ethernet0/0” ain’t mandatory on the e0/0: “ip address dhcp” command line for the Client and Server Devices within Ticket 7…

    But still it’s kind of an rather UGLY Cisco Trick, since both the Client and Server device are equally configured within Ticket (7) in terms of indeed the DHCP operation on their respective e0/0 interfaces (connected to the two switches) – but only our “Client” Device seems to work correctly regarding its DHCP operation on the e0/0 Interface in Ticket (7) :-(

  21. networktut
    April 22nd, 2015

    @Mike: The “client-id Ethernet0/0” is mandatory on the SERVER because R1 (DHCP Server) issues DHCP based on the MAC whist R2 does not. So CLIENT still gets the IP but SERVER cannot. This ticket is created to test if the candidate grasps how DHCP with option 61 operates.

    Please notice although CLIENT & SERVER have the same DHCP configurations but DHCP configurations of R1 & R2 are different so only CLIENT can get its IP address.

  22. Tony
    April 22nd, 2015

    @NetworkTut- What the answer of Ticket 2 ?

  23. Mike
    April 22nd, 2015

    Yes!!! – You’re damm right about the DHCP client/server trick within Ticket 7!
    Wasn’t aware about the Option 61 issue when solving the ticket, but just consulted the official CCNP Route and TSHOOT Study Guides (+ my personal study memory too), but couldn’t find anything (descriptions etc.) about the specific DHCP Option 61 feature…
    So, by joining Network Tut, the CCNP Candidate – most often – gains much more tech. knowledge etc. on certain Tech TSHOOT issues, than just reading the official CCNP Study Guides alone!
    Therefore: Thank’s a lot Network Tut for your – as always – very usefull tech. info, tips & tricks and the GREAT training tickets here!

  24. Steven
    April 22nd, 2015

    Challenge Ticket#2 Answers:
    A1: R2
    A2: DHCP
    A3: First, try give it a shoot, or more hints will continue here tomorrow – ok!?

  25. kapajo
    April 22nd, 2015

    I have some issues to view the devices configuration.

    I do not see any thing, after I click on RT I only see four sections;
    when I click on SW, I see sections for SW5 and SW6.

    I using chrome with latest flash plugins; same rendering with firefox

  26. networktut
    April 22nd, 2015

    @kapajo: Please type your commands into the boxes.

  27. Tony
    April 22nd, 2015

    @Steven- Got it!! Thanks… on R2, need to configure ‘default-router’ under DHCP pool…It was missing there..

  28. Steven
    April 23rd, 2015

    YESS, we got a WINNER here!!! – U’re definitely right on that!!! – Good Shot and 10/4 on that! :)
    Yheea, heard there was some problem with the ticket at the beginning, but it appear to be solved now :)
    Good luck at the exam!

  29. Anonymous
    April 24th, 2015

    On Ticket 2:
    There are interfaces ethernet0/2 on SW6 & SW5 (which are in access with vlan 12) configs,which are not present on the topology.
    @networktut : can you correct that please?

  30. networktut
    April 24th, 2015

    @Anonymous: It is not a mistake. In fact, R1 & R2 are connected through SW5 & SW6 via Vlan 12 like this:

    R1 (e0/2) —- (e0/2)SW5——(trunk via e1/0,e1/1)——SW6(e0/2)——–(e0/2)R2

    In the topology we only show the (logical) connection between R1 & R2 on Vlan 12 -> so you can deduce it must go through switches.

  31. Anonymous
    April 25th, 2015

    All the tickets questions are the same, so how will I know that which ones are the answers of ticket 1 or whichever ticket?

  32. networktut
    April 25th, 2015

    @Anonymous: Although having the same question but each ticket has different fault so you have to use your troubleshooting skill to find out where the fault is.

  33. asker
    April 25th, 2015

    I dont understand the diagram. how will client reach to server if they are in different vlan? are not routers just for DHCP ip assignment? and as for the ticket 2, if the answer is “default-router” should not SW6 be able to ping Server? after all, it is the default router.

  34. Route Professor
    April 25th, 2015

    Nice tickets! Quite challenging and in the spirit of the actual exam! Congrats networktut!

  35. networktut
    April 26th, 2015

    @asker: CLIENT and SERVER are in different VLANs so Layer 3 routing is required (on R1, R2, SW5 & SW6) so that CLIENT and SERVER can communicate. Please read the configuration of these devices to understand how it works. Or we have a tutorial explaining how it works at: https://www.networktut.com/vlan-routing

    In this topology SW6 cannot ping SERVER because there is an access-list applied on SW5 (based on company policy). This adds some difficulty to the troubleshooting and makes it harder to be resolved ;)

  36. Rcikfromva
    April 26th, 2015

    That was fun. Would be nice to expand to IPV6 and other issues found in the test. Lots of DHCP issues here. Good job on it though.

  37. Rolando
    April 27th, 2015

    Hello guys,

    I’m having trouble on Ticket 7 ( I think that the issue is on the DHCP on R1 where is configured as : ip dhcp pool SERVER
    host instead of network
    but I can’t find it to corrected on Question 3

    Q1: R1

    Does anyone has the answer?

  38. Cisco-101
    April 27th, 2015

    Ticket # 7 ?

  39. Sam
    April 27th, 2015

    Rolando + Cisco-101:

    Regarding Ticket # 7:

    Q1: SERVER!
    Q2: DHCP (check ok!)
    Q3: Pls study answer from networktut to Mike by April 22nd, 2015, and then try once more!
    (Hint: Ticket # 7 builds upon: DHCP “Option 61” MAC Addr. Based DHCP Operation, so command Parameter: “client-id Ethernet0/0″ is mandatory within our SERVER Config!
    Now, go and find correct Ticket # 7 Q3 Answer!
    Thank’s Guys!

  40. Sid
    April 28th, 2015

    Tikcte 6
    Q1: R1
    Q2: DHCP
    Q3: Under dhcp SERVER POOL, change the reservation host to

  41. classic
    May 9th, 2015

    Any solution to Ticket 3?

  42. classic
    May 9th, 2015

    Ticket 3: SW6 has different vlan in access port. :)

  43. classic
    May 12th, 2015

    What’s the answer for ticket 4?

  44. classic
    May 12th, 2015

    Ticket 4: IP Helper under interface VLAN. Try to figure which equipment is it. :)

  45. Leonid
    May 19th, 2015

    Thank you for such a beautiful challenge! I like it! I’ll look forward to the next one!

  46. Leonid
    May 19th, 2015

    I of course hope, that you’ve checked everything of it in GNS3 at least, before publishing

  47. Anonymous
    May 22nd, 2015

    Thank you networktut, good job done!
    I have a question, correct me please if I am wrong. In question #5, why DHCP server does not provide the single available IP for lease ? It should provide it regardless what mask will we have for network for lease or
    Thanks again for such nice simulator where we can practice and refresh our mind )

  48. networktut
    May 23rd, 2015

    @Anonymous: The DHCP Server R2 cannot provide an IP address because of this line:
    “ip dhcp excluded-address”
    So DHCP Server cannot assign to .10 to clients.

  49. Anonymous
    May 26th, 2015

    Hi networktut,
    thanks for the clarifications, I did not paid attention that it was the range )
    A couple years ago I passed the tshoot exam, and I think your simulator at least the same level as cisco has on their exam. Thanks again!

  50. networktut
    May 27th, 2015

    @Anonymous: This challenge only has 4 devices while the real exam has 4 routers and 4 switches. We are working on Lab Challenge 2 which is same level of Cisco exam, but for routers only.

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