Question: We recently changed IP schemes from `192.168.x.x` to `10.x.x.x` In doing so, I noticed that the prior network engineer had `ip default-gateway` in the configuration pointing to an old default gateway that no longer exist. I happened to notice this after our maintenance window ended.

```
ip default-gateway 192.168.10.1
ip classless
ip route 0.0.0.0 0.0.0.0 10.6.0.1
no ip http server
no ip http secure-server

```

**Question: Im assuming that I can safely remove this without affecting the current connection status, since 192.168.x.x scheme is no longer in effect and the `192.168.10.1` gateway is no longer in effect?**

Answer: 
A router that is configured to route does not use the `ip default-gateway`. It uses the default route, and you have that in the configuration.

Cisco has a document that explains the differences: *[Configuring a Gateway of Last Resort Using IP Commands](https://www.cisco.com/c/en/us/support/docs/ip/routing-information-protocol-rip/16448-default.html)*:

> 
> The **ip default-gateway** command differs from the other two
> commands. It should only be used when **ip routing** is disabled on
> the Cisco router.
> 
> 
> 

You can, and should, eliminate the `ip default-gateway` command if `ip routing` is enabled.

Configuring the `ip default-gateway` command on a device that has routing enabled is a rookie mistake that gets made all too often.
In addition to @RonMaupin's answer: if the defined gateway is unreachable (and even not configured on the network) there's no way that command can be relevant anymore. It can't be used, so it can safely be removed.