Configured API Gateways to route traffic to a back-end service using a VIP, which can resolve into one of the two data centers.
typically this resolves based on topology, so ideally it goes to one data center.. However when the traffic is flipped VIP resolves into a different IP, which in fact is seen in the nslookup response on the gateways.. how ever the traffic is not routed to that address.
Gateway has DNS caching by default.
Therefore gateway try to establish a connection to the old IP.
Release : 9.3 or later
Disable DNS caching
Add a new line to /opt/SecureSpan/Gateway/node/default/etc/conf/node.properties file,
node.java.opts = -Dsun.net.inetaddr.ttl=0
Restart the gateway to take effect
NOTE Also the route via http(s) assertion has keep-alive option enabled by default - may nee dot check that