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Subnet masking

G

guidedbyechoes

Member
I'm having issues with one of my labs it relies heavily on subnetting. I was wondering if there is a work sheet or program that can help with is? I am tasked with setting up a network and allocating ip addresses and the only thing thats given in the default gateway ip address and the mac addresses there is also a file server that must be configured. But we haven't even covered subnetting in class yet.... Any help would be welcomed!
 
Google is your best friend right now. Google subnetting for beginners or dummies or whatever, and you should find several well explained webpages about subnetting, of variable length.
 
You create subnets by masking out the n last bits of the IP address, like in a /24 is 32 bit IP minus the 8 last bits.
 
Are you trying to minimize the range of host IP's? Do you have a topology? You might get what you need from a SN calculator online.
 
You need to say more than "I'm having trouble with subnetting".

The concept is longer than someone will write in a post.

Do you have specific questions? Are there specific issues you need to resolve with your lab?

What are your first questions?
 
guidedbyechoes said:
I'm having issues with one of my labs it relies heavily on subnetting. I was wondering if there is a work sheet or program that can help with is? I am tasked with setting up a network and allocating ip addresses and the only thing thats given in the default gateway ip address and the mac addresses there is also a file server that must be configured. But we haven't even covered subnetting in class yet.... Any help would be welcomed!
Click to expand...

Are you approaching this as a VLSM or something else?
 
I don't know the technical term for what I'm doing they just call it subnetting here are the tasks.

Design an IPv4 addressing scheme and complete the Addressing Table based on the following requirements. Use the table above to help you organize your work.

a. Subnet the 192.168.1.0/24 network to provide 30 host addresses per subnet while wasting the fewest addresses.

b. Assign the fourth subnet to the LAB 124-C LAN.

c. Assign the last network host address (the highest) in this subnet to the G0/0 interface on CS Department.

d. Starting with the fifth subnet, subnet the network again so that the new subnets will provide 14 host addresses per subnet while wasting the fewest addresses.

e. Assign the second of these new 14-host subnets to the LAB 214-A LAN.

f. Assign the last network host address (the highest) in the LAB 214-A LAN subnet to the G0/1 interface of the CS Department router.

g. Assign the second to the last address (the second highest) in this subnet to the VLAN 1 interface of the LAB 214-A Switch.

h. Configure addresses on the hosts using any of the remaining addresses in their respective subnets.



They lost me at D. I do have the topology! on one network there is 2 pc and a switch. The other network is a switch a pc and a file server. The router connects them all together. It is right in the middle so I'm not sure if it technically belongs to one network or the other.
 
You can fit 30 hosts neatly into a /27 subnet (255.255.255.224) which also accounts for the network and broadcast addresses. This would make the first subnet 192.168.1.0 to 192.168.1.31 and useable host addresses 192.168.1.1 to 192.168.1.30. The next ranges follow the pattern, 192.168.1.32 to 192.168.1.63, etc.. The last useable host address of subnet two for example is 192.168.1.62. You can instantly get these ranges using Subnetmask.info.

This is a class C address space which I am ace with but even though my professor always said classes A and B were easier, I am horrible with them so I bust out this calculator most of the time.
 
PliotronX said:
You can fit 30 hosts neatly into a /27 subnet (255.255.255.224) which also accounts for the network and broadcast addresses. This would make the first subnet 192.168.1.0 to 192.168.1.31 and useable host addresses 192.168.1.1 to 192.168.1.30. The next ranges follow the pattern, 192.168.1.32 to 192.168.1.63, etc.. The last useable host address of subnet two for example is 192.168.1.62. You can instantly get these ranges using Subnetmask.info.

This is a class C address space which I am ace with but even though my professor always said classes A and B were easier, I am horrible with them so I bust out this calculator most of the time.
Click to expand...

I didn't mention it above but the default gateway is 192.168.1.32, so that wouldn't work would it. Wouldn't the first address in each range be the network ip and the last in each range the broadcast?
 
guidedbyechoes said:
I didn't mention it above but the default gateway is 192.168.1.32, so that wouldn't work would it. Wouldn't the first address in each range be the network ip and the last in each range the broadcast?
Click to expand...
Correctomundo! I would think the gateway would be 192.168.1.33 as it is the first address a router can use assuming a /27 subnet (could swear the gateway != network address, damn my professor would smack me). Anywho, this workbook is what my networking professor had us doing in semester 1. Very valuable exercises to understand it (check out page 79).
 
PliotronX said:
Correctomundo! I would think the gateway would be 192.168.1.33 as it is the first address a router can use assuming a /27 subnet (could swear the gateway != network address, damn my professor would smack me). Anywho, this workbook is what my networking professor had us doing in semester 1. Very valuable exercises to understand it (check out page 79).
Click to expand...

Thanks a million. I don't know what they plan on teaching us the curriculum is all screwed up since they are testing a new one on us. We have a guy with two certifications one in virtualzation and one in servers. He's leading the class with a 45 on this lab. The teacher had to reset it because people were bombing so hard. My first time I scored a 9. Out of a possible 100. :$
 
guidedbyechoes said:
I didn't mention it above but the default gateway is 192.168.1.32, so that wouldn't work would it. Wouldn't the first address in each range be the network ip and the last in each range the broadcast?
Click to expand...

Yep.

You also realize you need a different default gateway for each subnet. So just saying there is one of them doesn't make sense.

Assigning the default gateway to .32 is weird and I don't know why you/they would do that. By convention it's quite often the first/last IP in the subnet (.1 or .31 in this example, for the first subnet - .1 or .254 for the whole /24).
 
SecurityTheatre said:
Yep.

You also realize you need a different default gateway for each subnet. So just saying there is one of them doesn't make sense.

Assigning the default gateway to .32 is weird and I don't know why you/they would do that. By convention it's quite often the first/last IP in the subnet (.1 or .31 in this example, for the first subnet - .1 or .254 for the whole /24).
Click to expand...

All I can say is it's a cisco class. I learn sub net masking next week.....
 
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