Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people, just like you, are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions
Solved

Question on Zero-subnet in the test

Posted on 2013-01-03
8
369 Views
Last Modified: 2013-01-05
Hi Experts.

I am confused.

I have a question that says assign the 3rd usuable subnet to the serial interface of the router but note the sub zero subnet is not usable. The network is 192.168.1.0 / 240. this is just an example. Assign the last usable IP from the 3rd usuable subnet.

I know the first networrk is 0
2nd is 16
3rd is 32

What is my answer and shall i still consider the network 0 even though the question tells me to consider subnet zero is not usuable.

Thanks,
0
Comment
Question by:Zak
8 Comments
 
LVL 13

Expert Comment

by:Sandy
ID: 38742900
it depends on what device you are using this zero subnet because some of the devices are using the zero subnet.

http://www.petri.co.il/csc_ip_subnet_zero.htm
0
 
LVL 18

Accepted Solution

by:
Akinsd earned 250 total points
ID: 38742918
The 1st subnet = Zero subnet assuming that the command "ip subnet-zero" is enabled.
ip subnet-zero is enabled by default on every device
the question says, ip subnet-zero is unusable meaning it was disabled with the command
"no ip subnet-zero"
This means that the ip subnet "192.168.1.0" is not valid

Please confirm the slash notation used
Did you mean 192.168.1.0/24
Or 192.168.1.0 255.255.255.240 which would = 192.168.1.0 /28

The answer to this will determine what the network range is

I will assume you meant 192.168.1.0 /28

If that is the case
Your 1st subnet is 192.168.1.16 - 192.168.1.31
2nd Subnet is         192.168.1.32 - 192.168.1.47
3rd Subnet is          192.168.1.48 - 192.168.1.64

Your last assignable address in the 3rd subnet would therefore be
192.168.1.63


For experimental purposes
issue the command "no ip subnet-zero
then go on any physical or virtual interface and attempt to assign any ip address from
192.168.1.1 - 192.168.1.15
The switch will reject the ip because all of those belong to ip subnet-zero
0
 
LVL 2

Assisted Solution

by:perolin
perolin earned 250 total points
ID: 38743077
I agree with Akinsd.
Your example is not valid.  Eder it is 255.255.255.240 or /28.

Use IP Calculators, that can be found several in the Internet.


If your example is a IP Range you received from your ISP, then it is common, that you cant use the first and the last IP of the range. First is your NetworkID, Last your Broadcast.  ISP Information to you  192.168.1.0/28  (of Corse 192.168.0.0 is private)
Netzwerk:        192.168.1.0/28  
SubNetMask:   255.255.255.240
HostMin:        192.168.1.1
HostMax:       192.168.1.14
Broadcast:     192.168.1.15
Hosts/Netz:    14
0
Connect further...control easier

With the ATEN CE624, you can now enjoy a high-quality visual experience powered by HDBaseT technology and the convenience of a single Cat6 cable to transmit uncompressed video with zero latency and multi-streaming for dual-view applications where remote access is required.

 
LVL 18

Expert Comment

by:Akinsd
ID: 38744040
Assign the last usable IP from the 3rd usuable subnet.

Answer = 192.168.1.62

Pardon my typo above

Your 1st subnet is 192.168.1.16 - 192.168.1.31
2nd Subnet is         192.168.1.32 - 192.168.1.47
3rd Subnet is          192.168.1.48 - 192.168.1.63

Your last assignable address in the 3rd subnet would therefore be
192.168.1.62
the .63 is a broadcast address and is not assignable
0
 
LVL 9

Expert Comment

by:gt2847c
ID: 38744051
One does wonder why someone is teaching IP subnetting/addressing techniques that are 15 yrs out of date...
0
 
LVL 18

Expert Comment

by:Akinsd
ID: 38744099
It is obsolete and I agree, but it is still valid and available for whoever wants to use it.

I think the question is focused on testing the student's understanding of ip subnet-zero.

You will be amazed at how many Engineers lack the understanding.

I wouldn't write the question off though.

Just to recap
With ip subnet-zero enabled, your first usable subnet is 192.168.1.0 - 192.168.1.15
With ip subnet-zero disabled, your first usable subnet is 192.16.1.16 - 192.168.1.31
0
 
LVL 9

Expert Comment

by:gt2847c
ID: 38744146
I wasn't writing off the question, I answer a number of questions on EE that come with the advice "but don't do it that way"...  I just hope whoever's teaching the class provides the caveat that ip subnet-zero should not be used in anything other than a historical example...  

As to being amazed, I tend, rather, to be jaded on the lack of ability/understanding even at the carrier level...  Oh well...
0
 

Author Comment

by:Zak
ID: 38745862
Thank you all.

I know the difference now with your superb explanation.
0

Featured Post

Portable, direct connect server access

The ATEN CV211 connects a laptop directly to any server allowing you instant access to perform data maintenance and local operations, for quick troubleshooting, updating, service and repair.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Suggested Solutions

Hello to you all, I hear of many people congratulate AWS (Amazon Web Services) on how easy it is to spin up and create new EC2 (Elastic Compute Cloud) instances, but then fail and struggle to connect to them using simple tools such as SSH (Secure…
Creating an OSPF network that automatically (dynamically) reroutes network traffic over other connections to prevent network downtime.
After creating this article (http://www.experts-exchange.com/articles/23699/Setup-Mikrotik-routers-with-OSPF.html), I decided to make a video (no audio) to show you how to configure the routers and run some trace routes and pings between the 7 sites…
After creating this article (http://www.experts-exchange.com/articles/23699/Setup-Mikrotik-routers-with-OSPF.html), I decided to make a video (no audio) to show you how to configure the routers and run some trace routes and pings between the 7 sites…

856 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question