Currently I have a network and am running out of IP Addresses. I'm not sure if I change to /22 mask, if I will still be able to communicate with some of the other facilities where we use 10.10.30/24, 10.10.40/24, etc. Any advice appreciated, thanks.

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    In addition to the pretty good answers: you might want to consider using binary patterns in the future: using decimal 10 / 20 / 30 might be nice to look at for a human, but using 8 / 16 / 24 / 32 results in much cleaner subnetting and supernetting. ;-)
    – Zac67
    Jan 16, 2019 at 19:34
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  • good answer, I did as recommended and no problems
    – Anthony
    Dec 16, 2019 at 23:45
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2 Answers 2


If you change to /22 the network would be to, which doesn't overlap with your other addresses.

Whether your routing or filtering will let those source addresses out to your other branches, or whether packets will come back, is another question. But certainly it's possible to reconfigure your routing/access control to permit your /22 without clashing.

NB: The most complete question on addressing and masking is How do you calculate the prefix, network, subnet, and host numbers? which is the best place to look for understanding these things in detail.


Just to adjust jonathanjo's good response, changing the mask to /22, the network would be from to You can use ipcalc in Linux to check: $ ipcalc Address: 00001010.00001010.000010 10.00000000 Netmask: = 22 11111111.11111111.111111 00.00000000 Wildcard: 00000000.00000000.000000 11.11111111 => Network: 00001010.00001010.000010 00.00000000 HostMin: 00001010.00001010.000010 00.00000001 HostMax: 00001010.00001010.000010 11.11111110 Broadcast: 00001010.00001010.000010 11.11111111 Hosts / Net: 1022 Class A, Private Internet


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