IP Subnetting

Hi There,

Can anyone help understand subnetting... i have a Cisco SMB SRP541W unit.

this is what is is, i want to create a fw rule to allow traffic from a host based on its IP address, let's say that i want to allow traffic from 74.90.225.174 to my network, i don't know the source's subnet mask, just the IP.  When i create a rule i enter the IP address but a subnet mask is required, i entered or 0.0.0.0 and it fails (meaning the rule can't be create). if i use 255.255.255.255 it seems to create the rule but is it right?  Is the latter one the right choice if i don't know the source's sm?

thanks..
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jorge diazSEAsked:
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SeanSystem EngineerCommented:
255.255.255.255 is the correct answer as that means you are only allowing the IP you listed not a range.

you don't need to know the source sm only the IP
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JohnBusiness Consultant (Owner)Commented:
You appear to want a single IP address and 255.255.255.255 is the correct subnet mask for one IP. So if the rule is working, you are done.
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JohnBusiness Consultant (Owner)Commented:
@jorge diaz  - Thank you and I was happy to help.
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