I'm using the BUNDLE1841 with IOS ADVANCED SERVICES. I am having problems as ip subnet-zero command.
The router accept the command, but after to save the configurations, the show running, i don't see the ip subnet-zero on!
What it can be happening?
Sunday is quite correct. In very old versions of IOS the default was no ip subnet-zero. The default changed a LONG time ago and in all versions of code which run on the 1841 the default is to enable subnet zero.
When Cisco changes a default in the code they are pretty good about showing the value in the show running-config for quite a while. And the command has been displayed in code for a long time. In very recent versions of code several of theses defaults are no longer showing up, including subnet-zero. But the behavior is still enabled. Sundar's advice about doing no ip subnet-zero is a good way to check it out.
IOS doesn't display most default configuration. 'ip subnet-zero' is a very likely a default configuration in the IOS version you are using. The one way to confirm that would be if you configure 'no ip subnet-zero' the command would show up in the running configuration.