Dynamic Pool Members with DNS resolution

The LTM will attempt to resolve the FQDN to an IP address, and then create the pool member with that IP address. If the IP address can change, then you won't get the desired failover like you intend because it won't do the lookup every time a connection comes in. It'll only be resolved once upon creation of the pool member.

Can we use it in irule where we have the irule trigger a DNS lookup and check if the IP is enabled active in the pool and then pass traffic. Also if it resolves to new IP we can add that to the pool using irule?

I don't know if there's a way to do this. I would hope that if your business partner has a GSLB, they could provide you a VIP to point to rather than just one server IP address. That way, there would be fault tolerance on their end.

can you elaborate?

you can always check hostname in HTTP header via ltm and route as required.

thx

as JPV mentioned, you can use RESOLV::lookup and node command.

e.g.

 config

root@(ve11a)(cfg-sync In Sync)(Active)(/Common)(tmos) list ltm virtual bar
ltm virtual bar {
    destination 172.28.24.10:80
    ip-protocol tcp
    mask 255.255.255.255
    profiles {
        http { }
        tcp { }
    }
    rules {
        myrule
    }
    source 0.0.0.0/0
    source-address-translation {
        type automap
    }
    vs-index 14
}
root@(ve11a)(cfg-sync In Sync)(Active)(/Common)(tmos) list ltm rule myrule
ltm rule myrule {
    when HTTP_REQUEST {
  set host [HTTP::host]
  set dest [lindex [RESOLV::lookup @8.8.8.8 -a [HTTP::host]] 0]
  if { $dest ne "" } {
    node $dest
  } else {
    HTTP::respond 503
  }
}
when HTTP_RESPONSE {
  log local0. "client [IP::client_addr]:[TCP::client_port] server [IP::remote_addr]:[TCP::release] host $host"
}
}

 /var/log/ltm

[root@ve11a:Active:In Sync] config  tail -f /var/log/ltm
Feb 23 00:37:05 ve11a info tmm[4068]: Rule /Common/myrule : client 172.28.24.1:39112 server 206.190.36.45:0 host www.yahoo.com
Feb 23 00:37:13 ve11a info tmm1[4068]: Rule /Common/myrule : client 172.28.24.1:39113 server 74.125.200.99:0 host www.google.com
Feb 23 00:37:20 ve11a info tmm[4068]: Rule /Common/myrule : client 172.28.24.1:39114 server 64.4.11.42:0 host www.microsoft.com

Hi - this works now I believe in 11.6;

Populate pools This release includes the ability to configure a BIG-IP system with nodes and pool members that are identified with fully-qualified domain names (FQDNs). When configuring pool members with FQDN, addresses dynamically follow DNS changes. Fully dynamic DNS-managed pools may even be created.