I would like to setup two GSS in an redundant mode i.e. with same DNS rules. If one fails other should start servicing the DNS requests.
Both the GSS would be at two different locations and only one would service the requests at any point in time. So should I configure the two devices as
1) Primary GSSM and Standby GSSM
2) Primary GSSM and GSS
Keepalives are used to investigate health status of VIPs configured on CSS/ACE/CSMs or Servers. Each GSS polls each resource individually.If any GSS find any VIP/Server unavailable, it never responds with the IP of that particular server.So yes keepalives are ensuring failover of the application VIP but not "GSS failover"
AS I said earlier GSS is little different than other appliances with respect to redundancy.
All the GSSs are active and there is no primary/standby concept with GSS's DNS feature(as all GSS serve A records all the time).Primary & Secondary GSSM concept is only limited to which GSS will serve you the GUI to make changes and that's about it. You make dns rule changes at Primary GSSM and it pushes the changes to all other GSSs in the network.
On your Authoritative DNS servers you add DNS records for your application
gss1.abc.com. IN A a.b.c.d <-- A record for GSS1
gss2.abc.com. IN A a.b.c.d <-- A record for GSS2
Your Authoritative DNS server then send GSS1/GSS2 ip to the client's DNS server in roundrobin basis (Roundrobin is default DNS behaviour when multiple records are in DNS database. This roundrobin can be changed, for example on Microsoft DNS servers "http://technet.microsoft.com/en-us/library/cc787484.aspx')">http://technet.microsoft.com/en-us/library/cc787484.aspx")
Since both GSS are active the request could be serve by any GSS.
If one GSS fails then the client DNS server (after not gettting DNS queries answered by the failed GSS) will try the other available GSS.
Syed Iftekhar Ahmed