Irule for redirect when all pool members down, need one for each pool? and what is the standard practice for sorry server?

Hello Everyone,

I am new to F5. I have got a task to make a Strict failover VIP for my client. Referring to your sample irule

when HTTP_REQUEST { if { [active_members [LB::server pool]] == 0 } { HTTP::redirect "http://209.196.27.42/" } }

Please help me understand the meaning of ---HTTP::redirect "http://209.196.27.42/"--- part. When the members of pool in condition is down it will take the VIP down then how would it resolve the redirection. Per my understanding, which I know is wrong, there is no mention of new Pool.