Subnetting is Fun
Sun Mar 14th 2004, 10:07pm
Subnet Quiz Here is a web-based quiz I wrote a while back to practice your subnetting skills. Given an IP and a netmask, you derive the network and broadcast addresses. I wrote it to prep for the CCNA exam and to sharpen my on-the-job subnetting skills. For extra challenge, you can select "Advanced subnets" to have the program randomly give you the netmask in either dotted decimal (the default), hex, or slash notation.

The obnoxious cliche "practice, practice, practice" really describes the best way to get better at subnetting. It's part memorization, part basic math skills, but 90% practice. In other words, stopping after you understand how the bits work isn't enough, to be quick you need to repeatedly drill yourself with a program like this one.

I hope to publish a followup article on one way to easily subnet soon. If you're interested in the quiz program itself, you can read the PHP source.

Update March 26, 2009: I ran across an article called Subnetting Made Easy that gives an excellent and mercifully short explanation of how to subnet. The way he describes is exactly how I do it too. This technique works well, but I've always found it a little hard to explain to others, I'm glad someone else found a good way to convey it.



Visitor comments
On Sat Jun 12th 2004, 11:14pm, rene_enriquez_ posted:
thanks for this section...ive been practicing everyday...im studying for the ccna


On Sun Jun 13th 2004, 1:54pm, Steve Kehlet posted:
You're welcome! Glad to hear someone else finds it useful. Good luck taking the CCNA. For as hard as I studied, I passed by only 1 point (of 1000) :-).


On Sun Jun 27th 2004, 11:57pm, Guest posted:
nice work with the subnetting quiz mate.. everyday i take some time out to work out a few advance problems. Keeps me on top of the class.. Really cool


On Mon Jun 28th 2004, 2:07pm, Steve Kehlet posted:
Thanks, it's somewhat addictive isn't it. Cheers.


On Sat Jul 3rd 2004, 1:30pm, Gigafunk posted:
240........64......192..32....64....2...255...240...oh, what? oh yeah, words...yes words... I am posting, not grinding numbers(I have been at it awhile)Thanks for the practice....very very cool. Ok gotta get back.....248...160....224....32....252.......64.....128......


On Mon Jul 5th 2004, 12:07am, Steve Kehlet posted:
I updated the quiz page to automatically focus on the first box, so now your fingers never even need to leave the keyboard! Rapid fire subnet crunching! :-)


On Thu May 12th 2005, 7:19pm, Visitor posted:
Steve,
I have spent the last few days practicing my subnetting, and I can't find any other sources of new problems.

Thank you much.


On Fri May 13th 2005, 10:21am, Steve Kehlet posted:
Glad you've been enjoying it! I had to crank through a few more just now to freshen up my subnetting chops.


On Tue Jan 24th 2006, 10:32am, Scott H. posted:
Very nice. I started something like this in VB but never finished it. A timer with a running average would be really nice improvment. :)


On Thu Jul 20th 2006, 4:27pm, Redzzand posted:
Great site!! Very helpful to practice, and polish subnetting skills!!


On Fri Sep 15th 2006, 10:50am, Monty Python posted:
Yes, very useful. Well done!


On Tue Oct 3rd 2006, 3:35pm, Right on man... posted:
This rocks!! Thank you!!!


On Fri Oct 27th 2006, 12:46pm, SubnettingSusahBanget posted:
Mr Kehler.. thank you very much!!


On Tue Nov 28th 2006, 11:34pm, Visitor posted:
This is exactly what I have been looking for. You sir, are a freaking genius!


On Wed Nov 29th 2006, 1:57pm, Steve Kehlet posted:
Haha, thanks for posting Visitor, glad you like the tool.


On Thu Feb 8th 2007, 7:45pm, Joey posted:
Thanks for this great tool, I am taking my exam on the 23rd of this month. Thanks to you, I will have all the subnetting practice I will ever need! Great Work!


On Thu Feb 15th 2007, 4:34am, Visitor posted:
ee


On Fri May 25th 2007, 7:43am, Matt posted:
Thanks man my instructor used this site to teach our class of 20 to subnet. I owe you a cold one :)


On Sun May 27th 2007, 8:13am, BlueMerle posted:
Thanks Steve... This is great


On Tue May 29th 2007, 4:45pm, Steve Kehlet posted:
Matt and BlueMerle, I'm glad you liked the subnet quiz. It's great to hear feedback on this.


On Fri Sep 28th 2007, 9:27am, Jeff Eggenberger posted:
Very good practice tool! I am suprised at how quick I am getting at solving them. One suggestion, if there was a "skip" button, so you could skip past the easier ones without feeling like a failure when you see the big red INCORRECT... Thanks, Jeff


On Fri Sep 28th 2007, 10:50am, Steve Kehlet posted:
Jeff: glad you like it! I think the skip button is a good idea, I just added it.



On Wed Dec 12th 2007, 7:03pm, Kris posted:
I read the comments and they're ALL very true. I am indebted to you. Thank you for sharing this with us.

Ps. I look forward to reading the articles posted on the left.


On Thu Feb 14th 2008, 9:10am, Oscar posted:
Hey Steve, thanks for the article and the little quiz tool. Great stuff. You've been stumbled!


On Sun May 4th 2008, 4:49am, Visitor posted:
amazing thanks



On Wed Jul 2nd 2008, 2:02pm, jude posted:



On Wed Jul 2nd 2008, 2:02pm, jude posted:



On Thu Jul 17th 2008, 3:50pm, Ants posted:
Your the best, i think there should be a link from the cisco site. You should add a DONATE button, with all the people you must have helped by writing this you deserve some recognition.


On Tue Jul 22nd 2008, 4:34am, Tirtha posted:
Thanks! It helped me a lot to brushup my subnetting skills.


On Mon Aug 4th 2008, 6:34pm, Visitor posted:
hello Steve Kehlet, i stell got problem in subnetting any recomendations how easy to learn it?
my email is umnov@msn.com ,thanks


On Sat Aug 16th 2008, 1:52pm, sony posted:
Amazing work..


On Sun Sep 21st 2008, 6:51pm, Visitor posted:
Thanks champ for this site - good practice.


On Tue Oct 14th 2008, 2:11pm, Visitor posted:
This is awesome, This really helped more than anything I've read in a book!!


On Wed Oct 15th 2008, 10:42am, Mike posted:
Thank You Steve! This is great!


On Tue Oct 21st 2008, 3:28pm, Ryan posted:
Great tool thanks Steve!


On Mon Oct 27th 2008, 7:56pm, Robert posted:
Oh, thanks! This is great. I think I am getting the hang of it now. Thanks again for this great practice site. I also someday may take the CCNA test. We shall see!


On Mon Nov 10th 2008, 5:39am, Jerry posted:
Awesome tool! I'm taking my ICND1/CCENT tomorrow so this is good practice!


On Sun Nov 30th 2008, 8:43pm, Wayne posted:
This is great! I'm using this in prep for my 70-293 MCSE exam.


On Thu Dec 25th 2008, 7:33pm, Visitor posted:
I'm gearing up for the ICND too, this is great practice. Thanks.


On Thu Jan 8th 2009, 9:37am, daz posted:
thanx for subnetting tool ,im taking ccna and this is invaluable practice


On Thu Jan 15th 2009, 8:44pm, Visitor posted:
Excellent! I can see that there have been visitors since 2004, and this is still the BEST site ever that I have see on the internet to practice subnetting!!!! THANKS!!!!


On Wed Feb 25th 2009, 3:54pm, Visitor posted:
i do subnetting in class just to stay awake lol fun stuff


On Wed Feb 25th 2009, 3:54pm, Visitor posted:
i do subnetting in class just to stay awake lol fun stuff


On Mon Mar 2nd 2009, 6:45pm, Visitor posted:
I'm sitting for CCENT in a week- this has helped me really reduce my time to figure subnet, broadcast address and by extension beginning and ending host address for a subnet- great work!! Thanks for the help


On Tue Mar 3rd 2009, 10:08am, Steve Kehlet posted:
Thanks everyone for posting feedback, I'm very glad to hear it!


On Fri Mar 6th 2009, 6:00am, Jack posted:
At First Subnett is boring and complicated, but when you get to master it, IT IS FUN AND EASY TO DO!!!


On Wed Apr 8th 2009, 11:43am, Visitor posted:
ia m studying 70-291 for my MCSA and i found this exremely helpful . thanks
ronzo cartwtright MCp nashville ,tn


On Wed Apr 15th 2009, 11:54am, Jeannette posted:
Your quiz is great, I'm just learning subnetting and this is invaluable for drill practice. I'm studying for my CCNA.


On Sun May 3rd 2009, 5:39pm, Sam Bahani posted:
Good practice workshop for subnetting, thanks


On Wed May 6th 2009, 4:23am, Visitor posted:
Thank you very much! Excellent for CCNA prep :)

+ + _b


On Thu May 7th 2009, 12:11pm, Visitor posted:
that ip quiz is great
thank you much
did this stuff years ago and did not realize how rusty I am


On Sun May 10th 2009, 3:27pm, prabhu posted:
It is amazing to practice subnetting.it is quite good to practice asking subnet address and broadcast address.you could add questions like particular no of subnet or hosts needed.thats would be very greatful.cheers.


On Sun Jun 14th 2009, 7:14pm, Visitor posted:
Network address: 49.0.0.0
INCORRECT!
49.0.0.0 00110001 00000000 00000000 00000000
Broadcast address: 49.255.255.255
CORRECT! 00110001 11111111 11111111 11111111


Incorrect?


On Sun Jun 14th 2009, 8:43pm, Steve Kehlet posted:
Ahh, looks you had a leading space character in your response. That seems to cause this failure. I'll fix the code to trim whitespace, thanks for the report :-).


On Mon Jun 15th 2009, 12:03pm, Steve Kehlet posted:
Leading and trailing whitespace now trimmed. Thanks again for the report.


On Fri Jun 19th 2009, 3:10pm, Visitor posted:
this is an excellent way to practice subnetting ... thanks


On Tue Jun 23rd 2009, 5:13pm, Visitor posted:
Thanks for the practice. That link to the subnetting made easy page helped tremendously.


On Mon Aug 3rd 2009, 2:29pm, Dave posted:
Hey, thanks. This is useful and cool.


On Thu Aug 6th 2009, 12:20am, Steve posted:
Great site. I looked at it a while ago when I was doing my CCNA and always end up coming back to it to practice.



On Wed Sep 30th 2009, 1:32pm, Gregg posted:
Whoa, about time I came across something with immediate feedback. Been studying subnetting for a couple weeks and every time I think "I got it", I don't. Fabulous site you created here Steve. A Thousand Thanks to you kind sir...


On Wed Sep 30th 2009, 1:34pm, Gregg posted:
Whoa, about time I came across something with immediate feedback. Been studying subnetting for a couple weeks and every time I think "I got it", I don't. Fabulous site you created here Steve. A Thousand Thanks to you kind sir...


On Fri Oct 2nd 2009, 9:34pm, Visitor posted:
Great site. Just recommended it to the students in my Networking Admin Class for subnetting practice.

Thanks for the site.

Neil


On Fri Oct 9th 2009, 5:34pm, Visitor posted:
Hey Steve, it's a nice gadget, however it seems it outputs incorrect data.

IP address: 168.180.105.116
Subnet mask: 255.255.255.224
Network address is cool:
10101000 10110100 01101001 01100000
168.180.105.96

But the broadcast address is incorrect:

IP address:
10101000 10110100 01101001 01110100
invert subnet mask:
00000000 00000000 00000000 00011111

Your broadcast:
10101000 10110100 01101001 01111111
168.180.105.127

My broadcast:
10101000 10110100 01101001 01101011
168.180.105.107

Maybe there's still something with the spaces or the XOR doesn't work correctly. Or I'm doing something wrong. :-)



On Sat Oct 10th 2009, 4:54am, Visitor posted:
Ignore me, I was stupid.


On Mon Nov 9th 2009, 4:51am, Gavin Will posted:
Thanks... Been blasting through these now. Simple !



On Thu Nov 12th 2009, 10:58am, Dave posted:
Many Thanks, I have my CCENT in a weeks time and this site is really helping. Love the time feature too.

Cheers

Dave


On Sun Nov 22nd 2009, 10:40pm, Visitor posted:
Great Tool! I am studing for the CCna and this is a big help!

George


On Tue Dec 1st 2009, 12:19pm, Visitor posted:
Good stuff bro. I always come back when I feel rusty..


On Sun Dec 13th 2009, 6:28pm, Paola posted:
Very useful!!!


On Mon Dec 14th 2009, 8:47am, Visitor posted:
very nice for us beginners, thanks!


On Wed Dec 23rd 2009, 9:42pm, Visitor posted:
This was a treat to find! Much thanks and appreciation for this. Found it very helpful to get a solid grip on this and instant answers are a big plus. At some point you don't even need to use paper!!! Thanks a ton!!!!


On Sun Jan 10th 2010, 11:03pm, Ragachandrika posted:
This Quiz was really good!!! Really i dint feel subnetting to be easier at all before...

But after doing this quiz got to know completely class A,B and C subnetting....Thanku so much sir!!for creating such wonderful quiz...learnt a lot here...




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