Homework Help (CCNA 5.1 Introductions to Networking)

[Saint Grimm]

The second half of this semester, I ended up not paying as much attention as I should and now I'm working on my skills final and I'm lost... Would someone here mind explaining to me how I find the answers to these questions? I actually thought I had it down, but I can't even enter the given IP into packet tracer because it tells me the subnet is usable for that IP...

Please don't post links to calculators. I need to know how to figure it out manually.

The instructor provides IP/Mask and number of hosts for Subnet A and Subnet B -

IP/Mask: 172.16.32.0/24
Subnet A - 75 hosts
Subnet B - 10 hosts

Questions (I'm guessing they're all wrong at once I can't get packet tracer to take any info without saying it's invalid)

Subnet A -
Number of bits in the subnet - 0
IP mask (binary) - 10101100.00010000.00100000.0000000
New IP Mask (decimal) - No clue... Why does it get a "new" mask???
Maximum number of usable subnets, including the 0th subnet - 254
IP Subnet - 172.16.32.0
First IP host address - 172.16.32.1
Last IP Host address - 172.16.32.254


I haven't done subnet B yet.


How I got the above answers:

Number of bits:
total possible addresses for /24 = 256. 256 - broadcasting - network = 254. 254 - 75 = 179. The binary for 179 = 10110011, which cannot be put into a /d+, so that means 0 bits?

IP mask:
Just the binary of the IP... I don't know what an "IP mask" is and googling IP Mask only resulted in tutorials for hiding my IP address so I can do shady shit online and not get arrested...

maximum number of usable subnets:
same as number of bits. 256-1-1=254 meaning that's left over for hosts.

IP subnet:
Google came back with zip on this as well... So I'm just guessing it's the IP address?


First IP host - ip address + 1 on final decimal
Last IP host - IP address + max number of hosts on final decimal (254)


EDIT: Packet Tracer issue

In packet tracer, for the skills final, I have PC-A wirelessly connected to router-1, and copper straight through connecting router 1 and switch 1, as well as switch 1 and PC-B.

I went into PC-A IP config, tried to set the IP address as 172.16.32.1 and it automatically changed the subnet to 255.255.0.0 instead of 255.255.255.0, at once the IP given by our instructor is /24, I changed the subnet mask to 255.255.255.0 and got this error:

"Invalid IP for this subnet mask entered"

 

[Alabalcho]

If you are stumbling on such simple questions, why you're pursuing CCNA?

/24 mask means "255.255.255.0", or 11111111111111111111111000000. Number of usable host in /24 network is 256-2.
Go to your instructor, and ask your questions. And pay more attention next semester - the questions are going to be much more difficult.

 

[Saint Grimm]

The first half of the semester all we did was convert decimal to binary and back... I thought "oh this all there is to networking? this is easy" so I kinda did my own thing instead of listening to him talk because I thought it was easy... And now that's biting me in the ass. Got too cocky and I'm payin for it. If I had more time, I'd start reading the book where I left off, but I don't have the time. So I'll read the text book between this semester and next to catch up.

I got the 256 - 2 and 255.255.255.0 = 11111111.11111111.11111111.00000000 though... I'm afraid your answer only answered things I've already learned lol. Thank you for the reply though, I do appreciate the thought.

But /24 does not work in packet tracer... It says the IP he gave me to use is a class B address, and /24 is a class C... it auto inputs the 255.255.0.0 and if I change it to be 255.255.255.0 it tells me the IP is not valid with the mask...

So at once I was correct about /24 being 255.255.255.0 there's something else wrong other than my understanding of the /#.

 

[bill001g]

If it does not let you use the /24 mask then the software is outdated or bugged. The concept of classful networks is a outdated concept and is used more as a way to communicate the mask length..ie you say I want a class B network rather than say i want a /16.

The network 192.0.0.0/8 is a valid subnet mask. Not exactly useful because it mixes private and public networks but it is a valid mask.

 

[Saint Grimm]

I have packet tracer 6.3

I'll try updating (if there is a new version) and seeing if I get the same error. Thank you for the reply. I've been watching some different videos and think I MIGHT be able to figure out the parts I was unsure of before.

 

[Sandra_27]

In my experience with 4 kids from elementary school to college, about 1 third of the teachers don't even know about the homework packets, 1 third give a small extra-credit grade for the kids that did it, and about 1 third re-issue and assign the packets to be due as a grade in a week or 2.

The reading lists they send out are a suggestion of age appropriate books for sed grade level,or some site like http://academic.regis.edu/dbahr/GeneralPages/Cprogramming/HomeworkAssignments/HomeworksPage.htm - Basic informational stuff so when parents go to the library with their kids, there's a convenient list of reading to choose from.

When the kids get to HS and sign up for Honors and AP courses, summer homework may be required, but the parents and their students are aware of this before registration, it's part of the accelerated academic plan as it should be.

I never fought the summer homework battle, and rarely any homework battle during the school year and always Do My Calculus Homework. Any parent that would drive their kid to tears by insisting their child do homework is probably doing more damage than good as far as I'm concerned. All I know is that before we sit down to dinner, we first have to clear the table of stacks of magazines and books, - Calvin and Hobbs, Kid's National Geographic, Harry Potter, Percy Jackson, and yes, I've had to make the rule, "no reading during family dinner unless you want to share". (I think the books pile up during breakfast and lunch when I'm not there) So hey, I've done my job as a dad, my kids love to learn and read. My only fear is that the school requirements will turn them off to it by making it a chore. I'll try my best not to let that happen.