Re: Destination Host Unreachable
How is the firewall learning the route to the destination network (10.0.5.9)? Off hand, it looks like it could be a flapping route. If it's dynamic look for messages relating to the routing protocol (BGP / OSPF) if static, make sure you are not seeing interface drops.
When the ping is failing make sure you see the route in the Route Monitor or from the CLI type:
get router info routing-table all
- or -
get router info routing-table details 10.0.5.9