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Ernesto_M's avatar
Ernesto_M
Icon for Nimbostratus rankNimbostratus
Nov 17, 2020

Resolve 2 IPs at the same time, with failover in a 3rd one

In BIG-IP GSLB, I want to resolve a domain, for example, www.example.com, with 2 IPs at the same time (1.1.1.1, 2.2.2.2), and when these 2 IPs are down, resolve with a third IP (3.3.3.3). For example, in a nslookup this is what I want:

 

> nslookup www.example.com

Servidor: dns.google

Address: 8.8.8.8

 

Respuesta no autoritativa:

Nombre: www.example.com

Addresses: 1.1.1.1

         2.2.2.2

 

 

I achieved something similar using Wide IP, where I created 3 pools (1 per IP), the 2 main IPs are balancing in Round Robin and the 3rd IP is used as Last Resort Pool, the issue is that the 2 main IPs aren’t resolving at the same time, they’re balancing correclty, but no resolving at the same time, only one per nslookup request.

 

Another test I did was using Return to DNS as main action in pools (with previous Zone Records configuration), here I can resolve both IPs, but failover with 3rd IP doesn’t work.

 

 

Do you know what can I do to accomplish this?

  • Hello,

    My understand, in your scenario you can run with a single pool and a fallback IP:

    To get multiple answers, change the "Maximum Answers Returned" on pool properties.

    E.g.

     

    WideIP: www.my.domain

    Pools:  Pool_A

    Last Resort Pool: None

     

    Pool_A:

      Properties:

        Maximum Answers Returned: 2

      Members:

        1.1.1.1

        2.2.2.2

        Load Balancing Method:

          Preferred: RR

          Alternate: RR

          Fallback: Fallback IP

        Fallback IP: 3.3.3.3

     

    If you need to work with a last resort pool setup, you can:

     

    WideIP: www.my.domain

    Pools:  Pool_A

    Last Resort Pool: Pool_B

     

    Pool_A:

      Maximum Answers Returned: 2

      Members:

        1.1.1.1

        2.2.2.2

      Load Balancing Method:

        Preferred: RR

        Alternate: RR

        Fallback: None

      Fallback IP: 0.0.0.0

       

    Pool_B:

      Members:

        3.3.3.3

    .........

     

    I hope this helps.

     

    Best Regards

2 Replies

  • Hello,

    My understand, in your scenario you can run with a single pool and a fallback IP:

    To get multiple answers, change the "Maximum Answers Returned" on pool properties.

    E.g.

     

    WideIP: www.my.domain

    Pools:  Pool_A

    Last Resort Pool: None

     

    Pool_A:

      Properties:

        Maximum Answers Returned: 2

      Members:

        1.1.1.1

        2.2.2.2

        Load Balancing Method:

          Preferred: RR

          Alternate: RR

          Fallback: Fallback IP

        Fallback IP: 3.3.3.3

     

    If you need to work with a last resort pool setup, you can:

     

    WideIP: www.my.domain

    Pools:  Pool_A

    Last Resort Pool: Pool_B

     

    Pool_A:

      Maximum Answers Returned: 2

      Members:

        1.1.1.1

        2.2.2.2

      Load Balancing Method:

        Preferred: RR

        Alternate: RR

        Fallback: None

      Fallback IP: 0.0.0.0

       

    Pool_B:

      Members:

        3.3.3.3

    .........

     

    I hope this helps.

     

    Best Regards

    • Ernesto_M's avatar
      Ernesto_M
      Icon for Nimbostratus rankNimbostratus

      Hello cjunior,

       

      This worked for me, thank you very much!