What is the IP subnet zero command?

What is the IP subnet zero command?

The ip subnet-zero command provides the ability to configure and route to subnet-zero subnets. Subnetting with a subnet address of zero is discouraged because of the confusion inherent in having a network and a subnet with indistinguishable addresses.

Is 0 a valid subnet?

Some people may even try to argue that it is an invalid IP address because there is a 0 in third octet. However, today, this IP address is perfectly legal when it comes to subnetting.

How do I find my subnet mask Cisco?

Use the show run interface interface_name command to view both the IP address and subnet mask.

Can an IP address have 0?

0 address is going to be the network address and cannot be used by a device per se. Similarly, the . 255 address is going to be the broadcast address, which also can’t be used by a device. But there are other situations, and other masks, that could make that vary.

How do I find my subnet on my Cisco router?

To view the subnet mask, you can use the show ip interface command without the brief option. We can see that the IP addresses configured on the interfaces are correct (according to the IP address table) but notice that the status of the FastEthernet0/1 interface is showing as “administratively down”.

Can IP address have 0?

For example, IP addresses of networks with subnet masks of at least 24 bits ending in . 0 or . 255 can never be assigned to hosts. Such “last” addresses of a subnet are considered “broadcast” addresses and all hosts on the corresponding subnet will respond to it.

Can we use .0 IP address?

0 is perfectly legal these days. However, some devices (and firewall policies) believe that it isn’t. In the old “classfull” addressing scheme, IPs from 192.0. 0.0 to 223.255.

How do I use the zero subnet on my Cisco router?

Your Cisco IOS router, by default, has the command ip subnet-zero enabled on the router. Because of this command, the zero subnet can already be recognized. Do I really want to use the zero subnet? Just because something is there, doesn’t mean you should use it. That is true in the case of the zero subnet.

Why is my IP address equal to the subnet zero address?

So IP address equal to address of (any) subnet is not useable and will be rejected by CLI. The subnet zero is first (thus name ‘zero’ as addresses are counted from zero) subnet of a natural/implicit network block of classfull addressing scheme.

Is the use of subnet zero allowed in iOS?

The use of the all-ones subnet was explicitly allowed and the use of subnet zero is explicitly allowed since Cisco IOS Software Release 12.0. Even prior to Cisco IOS Software Release 12.0, subnet zero could be used by entering the ip subnet-zero global configuration command.

What is the binary equivalent of subnet zero?

Also, when you write the binary equivalent of the subnet zero address, all the subnet bits (bits 17, 18, and 19 in this case) are ones, hence the name. Traditionally, it was strongly recommended that subnet zero and the all-ones subnet not be used for addressing.