As YLearn points out, you need to determine if the switch is operating as strictly a layer-2 switch, or is it actually routing (layer-3). If it is routing, then you do not want to use the `default-gateway` or `default-network` commands.

You should not use the `ip default-gateway` commands on a router that is acting as a router, and the `ip default-network` command is really for IGRP, which doesn't understand the default route; you can use a static default route.

Cisco has a document that explains the differences: [*Configuring a Gateway of Last Resort Using IP Commands*][1]:

> Summary
> -
> 
> Use the **ip default-gateway** command when **ip routing** is disabled
> on a Cisco router. Use the **ip default-network** and **ip route
> 0.0.0.0 0.0.0.0** commands to set the gateway of last resort on Cisco routers that have **ip routing** enabled. The way in which routing
> protocols propagate the default route information varies for each
> protocol.

---

You also say that the `10.6.9.10` address that you want to use for the gateway is another switch. You need to make sure that address really is a gateway for that network. Do not confuse the layer-2 LAN with the layer-3 routing. The address you use as a gateway needs to be a router (or layer-3 switch) that knows how to get to other networks.

You should edit your question to include a good description (a diagram would be great) of how your network is connected, and the full switch configurations. That would help us give you a more specific answer.


  [1]: http://www.cisco.com/c/en/us/support/docs/ip/routing-information-protocol-rip/16448-default.html