Home > Ticket 13 – DHCP Helper-address

Ticket 13 – DHCP Helper-address

April 24th, 2018 in TSHOOT v2 Go to comments

Configuration on DSW1:

!
interface Vlan 10
 ip address 10.2.1.1 255.255.255.0
 ip helper-address 10.2.21.129
!

Note:
+ In this ticket you will find port-security configured on ASW1 but it is not the problem as the port-security is good (check with the “show interface fa1/0/1” command on ASW1 and you will see it is still in up/up state. Also if we use “ipconfig” command on Client1, we will see APIPA address (169.254.x.x).
+ 10.1.21.129 is the loopback1 interface of R4. The wrong IP address of 10.2.21.129 does not exist.

Ans1) DSW1
Ans2) IP DHCP Server (or DHCP)
Ans3) on DSW1 delete “ip helper-address 10.2.21.129” and apply “ip helper-address 10.1.21.129” command

Comments (30) Comments
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  1. Sam
    May 4th, 2015

    Helper:

    Good Point! – Yes, within several redundant Netw topologies, it’s quite often a good idea to use a logical I/F as the reference point within a DHCP Relay config, instead of using the physical ingress I/F on the DHCP Device like within the ip-helper case here.

    However, as discussed within posts above, this Loobback I/F method is used quite seldom within several Network topologies seen today and furthermore quite rarely described within most Cisco Studyguides etc. as regards normal best practice DHCP Relay configuration.

    So this way, the IP-helper Ticket present here is a real good case, to demonstrate the actual DHCP Relay issue :)

    Thank’s for sharing your DHCP Config tip with us!

  2. Joe
    May 30th, 2015

    @Network.tut and All:
    In new TSHOOTv2 exam, Client1 & 2 IP addresses are statically assigned so we’ll not see APIPA addresses at exam any more – Client1 & 2 always have IP addresses of: 10.2.1.3 & 10.2.1.4 –
    OK – If this is true, WHY is this Ticket # 13 then still actual and possible @ the new 01-135 exam???

  3. mahir
    June 4th, 2015

    can any one please tell me what is the question in ticket 13 ??????
    ok there is a problem with DHCP but where is the question ??????

  4. al
    June 7th, 2015

    mahir:
    As mentioned within TSHOOT Instructions, ALL TSHOOT Tickets (except Tickets: (2), 12, 15 and 16) have SAME question, say: “Client 1 & 2 can’t reach the external Web Server: 209.65.200.241, and you’re therefore requested to Troubleshoot the individual Ticket problems in order to find the root causes of theese problems”: (Problem: Device / Technology / Fix) – So it’s very simple, and no hokus pokus here…

  5. mahir
    June 9th, 2015

    thanks al.

  6. Asif
    June 11th, 2015

    Please explain strategy to identify DHCP range ticket? Where to ping ?

  7. Drago
    July 4th, 2015

    Hi ,

    I have a problems with this ticket. I changed the dhcp rang. The pc got an IP but I cannot ping to 209.65.200.241.It miss something between ASW1DSW1

    R4#ping 209.65.200.241

    Type escape sequence to abort.
    Sending 5, 100-byte ICMP Echos to 209.65.200.241, timeout is 2 seconds:
    !!!!!
    Success rate is 100 percent (5/5), round-trip min/avg/max = 18/23/32 ms

    R4#show ip dh
    R4#show ip dhcp b
    R4#show ip dhcp binding
    IP address Client-ID/ Lease expiration Type
    Hardware address
    10.2.1.5 0060.4744.A334 — Automatic
    10.2.1.7 0040.0BC4.A853 — Automatic
    R4#

    Could somebody explain me please^

  8. Mike
    July 4th, 2015

    Drago:

    If it’s the PT TT#15 u’r asking about – After fixing the DHCP range problem – u need to do a

    “wr” / “reload” on R4,

    to get the changes properly loaded on R4 – or – most often – you can simply do a R4:

    #copy run start
    #copy start run

    (The latter method – works most often, and is a little faster, than the first method.)

    Now checking for correct DHCP operation at R4:

    R4#sh ip dhcp bind
    IP address Client-ID/ Lease expiration Type
    Hardware address
    10.2.1.3 0060.4744.A334 — Automatic
    10.2.1.4 0040.0BC4.A853 — Automatic
    R4#

    Showing that all the (PT) DHCP stuff works just fine…

  9. Mike
    July 4th, 2015

    Drago:

    And also verifying connectivity towards the external WEB Server from Client 1:

    Packet Tracer PC Command Line 1.0
    PC>ping 209.65.200.241

    Pinging 209.65.200.241 with 32 bytes of data:

    Reply from 209.65.200.241: bytes=32 time=25ms TTL=122
    Reply from 209.65.200.241: bytes=32 time=25ms TTL=122
    Reply from 209.65.200.241: bytes=32 time=62ms TTL=122
    Reply from 209.65.200.241: bytes=32 time=76ms TTL=122

    Ping statistics for 209.65.200.241:
    Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),
    Approximate round trip times in milli-seconds:
    Minimum = 25ms, Maximum = 76ms, Average = 47ms

    PC>

  10. mayank
    July 17th, 2015

    @Networktut

    please help and tell how to solve this ticket it is not in metodo startegy

  11. mayank
    July 17th, 2015

    still not got way to figure out this ticket

  12. Drago
    July 19th, 2015

    tnanks

  13. mayank
    July 19th, 2015

    @ networktut and all

    can anyone help me how to figure out this ticket metodo startegy says nothing about this ticket

  14. Ahmed
    July 19th, 2015

    guys there is something wrong with this ticket ,

    first you can not ping 10.2.1.1 , (which is dsw1 vlan 10 ip address) , so how you would spot that the issue is on r4 dhcp especially that when you type the command ip config on client 1 you will find that the client has the correct ip configuration ,,,,,,, maybe this was valid on the old exam when u get APIPA address but i think its not anymore

  15. networktut
    July 19th, 2015

    @mayank, @Ahmed: This ticket does not appear any longer in the exam so please ignore it. Currently Client1 & 2 IP addresses are statically configured so DHCP is not used.

  16. 1 more to go
    July 29th, 2015

    I did not have ip helper address, no longer in exam,

    i also did not have Eigrp wrong As, or Harp track 10, but i will suggest you study all tickets here.

  17. Derrick
    October 1st, 2015

    I this ticket you must remove the excluded range of ip addresses from 10.2.1.1 10.2.1.253 and apply ip dhcp excluded-address 10.2.1.1 10.2.1.2.
    Still it will not ping the server because the router of 10.2.1.0 is not advertised on R4. Add the network and all is fine

  18. vj
    October 2nd, 2015

    @Derrick:
    U need to do a R4:
    wr/reload – or by the faster method:
    copy run start +
    copy start run
    to get the DHCP change properly loaded on R4
    Then it works just perfect :)

  19. Fp
    October 19th, 2015

    I am confused with this ticket. The clients have the ip addresses but are unable to ping themselves, each other or the gateway DSW1.. not sure if the sim is working or how this points to a DHCP issue?

  20. vj
    October 20th, 2015

    Clients are having valid IP addresses in every single ticket @ exam, no matter if they have a ok connection to dhcp server R4, or not –
    it’s just a trick, to see if they can fool you, and make you nervous @ exam – But just be cool there, and don’t let them! :)

  21. Chia’tAtA
    October 22nd, 2015

    Took me about 45min to cleared the Tshoot exams today with a 100% score.
    This was not in exams though.
    Thanks Networktut

  22. Anonymous
    October 23rd, 2015

    For the ticket 13, I did this already, on R4 delete ip dhcp excluded-address 10.2.1.1 10.2.1.253 and apply ip dhcp excluded-address 10.2.1.1 10.2.1.2 … however, the pc still cannot get valid ip address so that it can’t ping the web server of course, any ideas?

  23. Anonymous
    October 23rd, 2015

    Oooops, have to do wr and reload after the command, it works well!

  24. vj
    October 23rd, 2015

    Anonymous:

    Yheaa, isn’t that just real amaaazing – simply soo cool – right!? :)

    However, you could also try to use an even FASTER reload procedure on R4 after the DHCP config change on the device, like this:

    copy run start +
    copy start run

    and then see what happens :)

    This faster method Works about 90 – 95% of the times issued :-)

  25. Raj
    November 7th, 2015

    What is the question/problem for this ticket? All the other tickets had a single line description of the problem.

  26. vb
    November 7th, 2015

    Same question/problem for this ticket as for remaining (IPv4) tickets @ TSHOOT 300-135 exam

  27. Raj
    November 9th, 2015

    Another question how do we determine this is the issue if the description/problem is the same?

  28. vb
    November 10th, 2015

    Well, the problem is the same ticket by ticket @ exam, but the reason WHY the Client’s can’t ping the external web server (209.65.200.241) is indeed different among the exam tickets – That’s why you gonna troubleshoot the various faults in the tickets @ exam.
    So, as an example – if the clients (quite rarely) should be equipped with APIPA based IP addresses @ exam, and thus ain’t able to ping the ext. web server – it’s your job to find out WHY this (DHCP) fault occured in the actual ticket @ the exam, by using your achieved CCNP TSHOOT skills!

  29. Shambuling
    December 18th, 2015

    Dear Ganesh,The cut off is considered to have gone up this time. And there are a lot of sedutnts who have calculated their scores above 210-215 or so. Overall, sedutnts found both the papers comfortable (and not too difficult). Regards,Rau’s IAS

  30. Paulo
    December 18th, 2015

    Hi Kamal,You’ll need to connect to the seairl/console port of the AP-5131. I would start by verifying that the seairl port on your laptop/desktop works can you connect to anything else. Are you sure you have the correct seairl cable? I believe it should be the same as a Cisco console cable. When you have that working you’ll know that isn’t your issue then just connect to the AP-5131 with 19200-8-N-1 and you should be set to go.Good Luck!

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