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sorry sorry sorry just two questions

Discussion in 'General Cisco Certifications' started by kobem, Oct 4, 2007.

  1. kobem

    kobem Megabyte Poster

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    i will eat my head right now

    just asking some new questions

    1- 172.160.0.0/16 is a classful network address but IS 172.16.0.0/24 CLASSFUL or CLASSLESS?

    2- pc1 to router 1 (ethernet) , router1 to router 2 (serial) , router 2 to pc2 (ethernet) ( connections are like that)

    after configuring router1 and router 2 (assigning ip addresses) without using any routing protocols or static route ...

    may i ping from pc1 to serial interface of router1 ?

    or from pc2 to serial interface of router 2 ?
     
    Certifications: CCNA
  2. hbroomhall

    hbroomhall Petabyte Poster Gold Member

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    Both are classless descriptions.
    No way of knowing. You say they were configured, but then say no static routes, so they weren't configured. So result is in the lap of the gods.

    Harry.
     
    Certifications: ECDL A+ Network+ i-Net+
    WIP: Server+
  3. r.h.lee

    r.h.lee Gigabyte Poster

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    kobem,

    What is the binary for 172. decimal?

    Can you trace the encapsulation and decapsulation process from PC1 to the serial interface of router1? Do you have equipment to find out the answer to this question?

    Can you trace the encapsulation and decapsulation process from PC2 to the serial interface of router2? Do you have equipment to find out the answer to this question?
     
    Certifications: MCSE, MCP+I, MCP, CCNA, A+
    WIP: CCDA
  4. Tinus1959

    Tinus1959 Gigabyte Poster

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    Classfull looks at the binary bits only. If you use the form /xx it is automaticly seen as CIDR.
     
    Certifications: See my signature
    WIP: MCSD, MCAD, CCNA, CCNP
  5. kobem

    kobem Megabyte Poster

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    oh no not 172.160 it is 172.16.0.0/16 sorry again
     
    Certifications: CCNA
  6. kobem

    kobem Megabyte Poster

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    172.16.0.0/16 is classless why ?

    maybe 172.16.0.0/24 cause it has not the default subnet mask

    ......


    from pc1 to serial int. of router 1 >>>>>> my ping shouldn't be succesful without routes ?

    from pc2 to serial int. of router 2 >>>>>> my ping shouldn't be succesful without routes ?
     
    Certifications: CCNA
  7. hbroomhall

    hbroomhall Petabyte Poster Gold Member

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    Because you have shown it in CIDR form, hence classless.

    No connection would be successful without routes. All TCP/IP based machines have a routes table in some form or other.

    Harry.
     
    Certifications: ECDL A+ Network+ i-Net+
    WIP: Server+
  8. kobem

    kobem Megabyte Poster

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    second one is alright but first one ? :(

    172.16.0.0/16 is a major network and it has to be classful oh my god this is damn!:eek:
     
    Certifications: CCNA
  9. hbroomhall

    hbroomhall Petabyte Poster Gold Member

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    No 'has to' about it.

    If you are in a CIDR environment then there are no classes involved, even though your network allocation may look like an old class. And in the real world these days very few network allocations align with a class.

    Harry.
     
    Certifications: ECDL A+ Network+ i-Net+
    WIP: Server+
  10. Tinus1959

    Tinus1959 Gigabyte Poster

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    Kobem,
    Don't you read what we answer?
    Because you use the form 172.16.0.0 / 16 it is CIDR. It's a definition. If you use the / notation, it is classless.
     
    Certifications: See my signature
    WIP: MCSD, MCAD, CCNA, CCNP
  11. wizard

    wizard Petabyte Poster

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    Kobem,

    To help with everyone's sanity, what certifications are you currently working towards? You seem to be jumping from one subject to another without even giving yourself time to grasp the basics. This is not me having "a go" at you this me telling it as I see it.
     
    Certifications: SIA DS Licence
    WIP: A+ 2009
  12. r.h.lee

    r.h.lee Gigabyte Poster

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    kobem,

    What is decimal 172. in binary?
     
    Certifications: MCSE, MCP+I, MCP, CCNA, A+
    WIP: CCDA
  13. Liqua

    Liqua Bit Poster

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    It all depends upon how the routers & PC's were configured.

    Assumptions:
    - PC1 & PC2 are on different subnets
    - PC1 is on the same subnet as R1 and similar for PC2 & R2
    - PC1 has it's default gateway set to be the IP address of Router1, and similar for PC2 & R2
    - The routers were configured correctly (assigned IP's and interfaces opened, link between R1 & R2 correct)
    - No routing protocols are running and no static routes entered onto the routers

    From PC1 then you will be able to ping the ethernet port on R1, ping the serial port on R1 & ping the serial port on R2. You will not be able to ping PC2.

    The router automatically adds directly connected networks into the routing tables and knows how to route between them.

    Liqua.
     
    Certifications: CCNA, SND, ITIL Foundation
    WIP: CISSP
  14. Liqua

    Liqua Bit Poster

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    double post
     
    Certifications: CCNA, SND, ITIL Foundation
    WIP: CISSP
  15. Morne Louw

    Morne Louw Byte Poster

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    Definitely classless (and i am not all to grounds with subnetting and the like right now anyway) don't know about the other question.
     
    Certifications: ECDL, OCN Level 2 HTML, A+,MCDST,70-270
    WIP: MCSA/MCSE
  16. MacAllan

    MacAllan Byte Poster

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    I don't think you can ping from host PC1 to the serial port on R2 (unless you are using an inferior SIM :dry) as R2 will not know the route back to PC1 for sending the echo reply.
     
    Certifications: A+, N+, CCNA
    WIP: CCNP, Linux+
  17. Liqua

    Liqua Bit Poster

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    My mistake - you're right - the scenario described would allow PC1 to ping the serial interface on R1 but not R2 .. No route back as it's not entered. That's what you get for having a frame relay switch in the middle and thinking it would work the same as a direct connection and being too lazy an arse to check it for real. :oops:

    Oh, and no Simulators here - a trio of 2612's, a pair of 2950 switches and a 2520 "frame-relay" router - not found one yet that works the same as the real thing :biggrin
     
    Certifications: CCNA, SND, ITIL Foundation
    WIP: CISSP
  18. r.h.lee

    r.h.lee Gigabyte Poster

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    Liqua,

    The term is "frame relay switch" instead of "frame-relay router." :p
     
    Certifications: MCSE, MCP+I, MCP, CCNA, A+
    WIP: CCDA

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