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My Windows router is set up to use as its IP address. I have just added a new IP address: However, I am unable to ping this new IP address from my desktop. I have added to my desktop, which is unable to access.

I am also unable to ping from within the server. I can ping with no problems. I have also discovered that I am unable to ping from this machine. This leads me to believe there is a firewall getting in the way. Can anyone suggest a way to debug this? I have tried completely disabling the Windows firewall, but this doesn't seem to have any effect.

As an aside, can you confirm that my use of the slash notation is correct? I believe that saying is the same as saying with a subnet mask of What is the correct name for this notation?

Thank you for your time.

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migrated from Nov 25 '10 at 16:50

This question came from our site for system and network administrators.

Try disabling and then re-enabling your network connection(s). – Khaled Nov 25 '10 at 16:40
Do you have defined in c:\windows\system32\drivers\etc\hosts? Are you trying to assign two IP addresses to a single network card in your PC? How are you adding a second IP to your router? Do you have routes set to send traffic to .16 and .18 subnets? – dmah Nov 25 '10 at 17:15
@dmah: 1) /etc/hosts can mess up the name localhost but never the address 2) Multiple addresses per interface are valid. – grawity Nov 25 '10 at 18:16

All working address should be pingable. Try using ipconfig to list all your configured addresses. is the same as address is a network and usually defined as Address is usually on a network specified as The router for this network is usually found at or Addresses and have special meaning and are not usable as host addresses. The suffix /31 does not specify a usable network, as both addresses are special addresses. THe suffix /30 specifies the smallest usable network (2 host addresses).

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What kind of router do you have? Just a standard in-home router found at Walmart or Best Buy? If that is the case. I am not sure you can 2 different networks or vlans on a single in-home router.

However, try setting subnet mask to on your computers. This would make a single network -- This network would cover every IP between to With the valid host IPs (IPs you can configure your computers with), anything between to That is because the first IP ( and and last IP( of a network can not be used. First IP is used to define the network itself. While the last IP is used for network broadcasts.

Don't forget to set a default gateway that points to your router. Just like BillThor said, the standard is normally the first valid host IP of the network,, or the last valid host IP,

I'll change my answer if more information is provided.

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