Cisco-specific network engineer questions

  1. What is a wildcard mask, and how is it different from a netmask?
  2. How do you configure a Cisco switch or router? What are the steps needed?
  3. How would I place an interface into trunking mode?
  4. How do you shutdown an interface on a router or switch?
  5. What is VTP?
  6. What is VMPS?
  7. What is SPAN/RSPAN?
  8. What is flow/netflow?
  9. What is TACACS? Radius?
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11 Comments on Cisco-specific network engineer questions

  1. nalini
    Posted 12/22/2005 at 9:43 pm | Permalink

    4.
    on router or switch to shutdown the interface commands are:
    router>enable
    router#config t
    router(config)#int s0
    router(conf_if)#no shutdown

  2. Jason Welcker
    Posted 12/24/2005 at 5:51 pm | Permalink

    3.
    conf t
    int foo
    switchport mode trunk
    exit

    4.
    conf t
    int foo
    shutdown
    exit

    Where foo equals the interface you’d like to trunk/shutdown.

    5. Virtual trunking protocol allows easier management of VLANs over multiple switches by implementing VTP Server(s) and a VTP domain. When you configure a new VLAN on one VTP server, the VLAN is distributed through all switches in the domain. This reduces the need to configure the same VLAN everywhere. There is much more to VTP, but I assume in an interview you wouldn’t need to get as deep as VTP Pruning, VTP transparent mode, etc..

  3. Anjan
    Posted 6/22/2006 at 1:06 pm | Permalink

    9. TACACS+ is a security application used with AAA that provides centralized validation of users attempting to gain access to a router or network access server.
    TACACS+ services are maintained in a database on a TACACS+ daemon running on a UNIX, Windows NT, or Windows 2000 workstation.

    TACACS+ provides for separate and modular authentication, authorization, and accounting facilities
    RADIUS is a distributed client/server system used with AAA that secures networks against unauthorized access.

    AAA means Authentication Authorization Accounting

  4. Anjan
    Posted 6/22/2006 at 1:12 pm | Permalink

    6. A VLAN Membership Policy Server or “VMPS” is a network switch that contains a mapping of device information to VLAN.

  5. Ranjha Singh
    Posted 11/3/2006 at 10:37 am | Permalink

    TACACS+ & RADIUS is protocol, which is used to authentication not a application.

  6. Posted 12/10/2006 at 9:13 pm | Permalink

    1. What is a wildcard mask, and how is it different from a netmask?

    > netmask determines the subnet part of the ip address

    example
    255.255.0.0 class b. the netmask is 255.255

    wildcard mask is the opposite. u see this in ospf.

    0.0.255.255 .. the 255.255 here defines the host portion. its a wild thing really

    2. How do you configure a Cisco switch or router? What are the steps needed?

    >enable
    #configure terminal

    configs are slightly similar

    3. How would I place an interface into trunking mode?

    en
    config t
    int s0/0
    switchport mode trunk encapsulation dot1q|isl

    4. How do you shutdown an interface on a router or switch?

    en
    config t
    int s0/0
    shutdown

    5. What is VTP?

    virtual trunking protocol. set up on switches to manage vlans.

    6. What is VMPS?

    VLAN membership policy server. maps information regarding vlan

    7. What is SPAN/RSPAN?

    Switched port analyzer. remote switched port analyzer.
    you can monitor traffic flowing to a port from another port.

    8. What is flow/netflow?

    protocol for collecting IP information

    9. What is TACACS? Radius?

    terminal access controller access control system
    remote access dial in user service

    security enabled by aaa
    authentication, authorization, accounting
    provides a means of validation of users gaining access to a router

    accounting not used with radius.

  7. Hariharan
    Posted 5/25/2007 at 1:25 am | Permalink

    Netmask defines the class. whereas wildcard mask defines the allow or deny which is used in the access-list. Means, 0.0.0.255 represents… 0=match; 1=ignore; so here in this wc mask all 0 octets should match exactly where as .255 octet can be anything.

  8. sandeep yadav
    Posted 5/30/2007 at 4:03 am | Permalink

    on router or switch to shutdown the interface commands are:
    router>enable
    router#config t
    router(config)#int s0
    router(conf_if)# shutdown

    this will shut your active interface

  9. Ameet Mathrani
    Posted 8/17/2007 at 10:12 am | Permalink

    Following is wrong:

    nalini said,
    4.
    on router or switch to shutdown the interface commands are:
    router>enable
    router#config t
    router(config)#int s0
    router(conf_if)#no shutdown

    Right way:
    on the interface of the router/switch,which you want to shutdown,just enter the command “shutdown”

  10. Jah
    Posted 9/21/2007 at 2:48 pm | Permalink

    The wildcard mask is usually a string of binary digits shown over the subnet number, telling the router which parts of the subnet number to look at. A binary “0″ over a particular digit in the subnet number says “Pay attention to this digit.” A “1″ says “Ignore this digit.” In a wildcard mask, all the binary “0″s in a conventional subnet mask are replaced by “1″s and all the “1″s are replaced by “0″s.

  11. prajith mp
    Posted 2/26/2008 at 11:07 pm | Permalink

    for trunk mode in switch interface
    #int fa 0/1
    #switchport trunk allow vlan (vlans you required seperated with coma)
    #switchport mode trunk [isl](encapsulation dot1q)

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