Default gateway question

[Arcaneuk10]

Dear all

a quick question, not sure if I am on the right track, here goes.

A system on your network is configured with the following address: 172.31.34.255/20. Which of the following should be configured as the default gateway in order to communicate with remote host assuming the router interface is the first in the subnet?

what I have done so far.

I calculated the subnet id, from above address which I make to be 172.31.32.0

and I calculted the broadcast address to be 172.31.16.255

Then I said the first usable ip address is 172.31.32.1 (add 1 in the last octet)

and the last usable address is 172.31.16.254 (minus 1 in the last octet)

so my range is 172.31.32.1 - 172.31.16.254

next I think i will want my default gateway will be the first usable number which is

172.31.32.1, is this right, or am I complicating the question. Grateful for some guidance regarding this.

regards

Arcaneuk

[Flavio Miranda]

Hi,

For a subnet with 172.31.34.255/20

you can have all the range below:

172.31.32.1 - 172.31.47.254

This means that the gateway can be any address between this range.

You can use a subnet calculator to confirm that.

[Arcaneuk10]

H i Flavio

many thanks,for your reply, which subnet calculator do you use to confirm this?

regards

Arcaneuk

[Flavio Miranda]

I often use this onehttp://www.subnet-calculator.com

[Arcaneuk10]

cheers, many thanks

[saif musa]

Hi,

Please, find below...

*Which of the following should be configured as the default gateway= The IP address which you have already chosen to be your LAN network gateway address. e.g gateway address inside one of your LAN PCs.

*In order to communicate with remote host = You got to have a routing table inside your router to be able to communicate with remote hosts outside your network.  

* Router interface is the first in the subnet = 172.32.31.1 255.255.240.0 

Regards

[Arcaneuk10]

many thanks Saif, thank you for your help.

regards

Arcaneuk

[paul driver · Accepted solution]

Hello

172.31.32.0/22 as already stated will give you 172.31.32.1 -172.31.47.254

As you have requested the D/G can be 172.31.32 1 - so the L3 interface for this subnet will have this ip address.

All you clients will have this ip as it D/G

Lasty 172.31.34.255 is a valid ip address and this can be used on any device attached to that subnet with the addressing below:

IP  =172.31.34.255
Subnet = 255.255.240.0
D/G = 172.31.32 1

res
Paul

[Arcaneuk10]

Hi Paul

Many thanks, very useful in helping me understand this. 

Regards 

Arcaneuk10