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

[Ernesto_M]

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?

[cjunior · Accepted solution]

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]

Hello cjunior,

This worked for me, thank you very much!