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  1. Hi Shinu,

    It will depend on the host but Windows for example uses a metric to determine which default gateway to pick.

    Try a “route print” on a Windows machine when it’s connected with two network interfaces and has default gateways. You can see which default gateway it will prefer.

    Rene

  2. Hi Miguel,

    In the ARP table you only find MAC addresses of devices in the same subnet. When your PC wants to reach something that it not in the same subnet then it will send it to the default gateway. You will only find one entry in the ARP table for everything that is not in your own subnet: the router MAC and IP address, that’s it.

    Rene

  3. Hi Rene,

    I was reading your lessons since one month onwards thanks for great explanation…

    I have one small query

    HOST — SWITCH — HOST
    10.10.10.2 — SWITCH ---- 20.20.20.2 / 24

    will ping work for above scenario … My answer would be No … Since we can’t add the default gateway is that correct answer…

    Tried this scenario on GNS,while connecting the host to switch via Ethernet cable it’s throwing error so i thought we could not able to configure Default gateway
    it’s throwing an error.

    Please help me in understanding this

  4. Hi Rene/Moderators,

    With regards to this questions and answers
    "
    Hi Chris,

    IP route is used on a router to enter something in its routing table. The effect will be the same…

    Devices like switches don’t build a routing table so that’s when you need to use the ip default-gateway command. Also, on a router you can use it if you disable the routing table with “no ip routing”.

    Rene
    "

    Am trying to fix some problems on L3 switches with ip routing enabled, which have eg.

    ip default-gateway 10.10.10.10
    and
    ip route 0.0.0.0 0.0.0.0 20.20.20.20

    Since ip routing is enabled, is the ip default-gateway 10.10.10.10 overridden?

  5. Hello Ian.

    This is a very good question. This often causes confusion.

    The ip default-gateway command is used to allow the switch itself to communication with devices outside its subnet. If you have an SVI configured, say interface vlan 10 with an IP address of 10.10.10.5/24, in order for this interface to communicate with the administrator’s PC on another subnet for telnet or SSH connectivity, then it requires a default gateway. You would enter the command ip default-gateway 10.10.10.1. This is similar to the default gateway you configure on a PC. Note that this has NOTHING to do with the routing functionality of the L3 switch. This is called a default gateway.

    The ip route 0.0.0.0 0.0.0.0 20.20.20.20command actually places this default route within the routing table and is used to route packets that enter and exit the L3 switch. This is called a default route.

    I hope this has been helpful!!

    Laz

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