Member Avatar for socheata

Dear all,


Can you explain me about subnetmask? how can I find the subnetmask and number of host?


Thank!

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Member Avatar for ryan461

The subnet mask is something you can set depending on how large you want the network to be. Basically a 255.255.255.0 translates to 11111111.11111111.11111111.00000000

Theres 24 1s and 8 0s. To figure out how many hosts you have raise 2 to the number of hosts. Then you subtract 2 for the network and broadcast address of that network. SO in this case, 2^8 = 256. 256-2 = 254. There you have 254 IPs to hand to devices. The more 0s you have in the mask, the more hosts per network. The more 1s you have, the more networks you can create.

Member Avatar for rch1231

Hello,

Your subnet mask should have been provided by your hosting server service provider. Basically what it does is determine how many IP addresses are on your local segment of the network so the system knows what addresses it must go out through the gateway to access. i.e. If you were assigned 8 Ip addresses (say 120.5.72.8 through 120.5.72.15) your subnet mask would be 255.255.255.248 or
255.255.255.255 - 0.0.0.8


Here is a table which may help.

ID	# Bits	Number Hosts	Usable Hosts	Netmask		Note

6	/6  	67108864	67108862	 252.0.0.0  	

7	/7 	33554432	33554430	254.0.0.0 	

8	/8 	16777216	16777214	255.0.0.0 	Class A Network 

9	/9 	8388608		8388606		255.128.0.0 	

10	/10 	4194304		4194302		255.192.0.0 	

11	/11 	2097152		2097150		255.224.0.0 	

12	/12 	1048576		1048574		255.240.0.0 	

13	/13 	524288		524286		255.248.0.0 	

14	/14 	262144		262142		255.252.0.0 	

15	/15 	131072		131070		255.254.0.0 	

16	/16 	65536		65534		255.255.0.0 	Class B Network 

17	/17 	32768		32766		255.255.128.0 	

18	/18 	16384		16382		255.255.192.0 	

19	/19 	8192		8190		255.255.224.0 	

20	/20 	4096		4094		255.255.240.0 	

21	/21 	2048		2046		255.255.248.0 	

22	/22 	1024		1022		255.255.252.0 	

23	/23 	512		510		255.255.254.0 	

24	/24 	256		254		255.255.255.0 	Class C Network 

25	/25 	128		126		255.255.255.128 	

26	/26 	64		62		255.255.255.192 	

28	/28	16		14		255.255.255.240	

27	/27	32		30		255.255.255.224	

29	/29 	8		6		255.255.255.248 	

30	/30 	4		2		255.255.255.252
Member Avatar for socheata

Thanks for your answer.

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