What's wrong when a broadband connection lacks a default gateway number?

Question

Its tricky and its the installation personnel are in charge with the typing of the numbers but I noticed that they'd only put numbers on the subnet mask and ip address and the default gateway remains blank. It could be this that prevents the input of signal from the antenna. So is it possible to have a connection functioning even though the DNS server number and gateway number are void?

Answer 1

The default gateway is used when your computer tries to connect to an ip address which is not on the same subnet as it (your computer). It needs to know which network device on your subnet has a connection to other subnets, the default gateway is used when no other more specific routes exist. You can check which other routes are setup on your computer by clicking start -> run -> cmd <enter> -> route print <enter> -> exit <enter> [takes you back to windows]

So without any routing information your computer can only connect to other network devices on the same subnet, for example:

Your IP: 192.168.1.50 subnet mask 255.255.255.0

Every address starting with 192.168.1 is on your subnet, anything else is not on your subnet, so without a default gateway / specific routes, you can communicate to another network device with the ip of 192.168.1.5 but not with an ip address like 192.168.2.2 or 202.37.168.1 etc.

So having no default gateway will not stop a wireless network connection from working (or the input of signal from the antenna), but if your computer does not know how to route an IP frame then it will not be able to transmit the frame (as it has nowhere to go).

If you are using a proxy server on your subnet which handles browsing the web etc then it should be ok, if you have no DNS server specified then this will almost certainly cause you problems (although once again a proxy server may solve this problem for you).

If you provide more information about what you are doing which is not working eg browsing the web, or sending email etc and the settings from within the program eg Internet Explorer, Outlook, etc then we can be of more help.

Making some assumptions, you will need a default gateway ip address as well as that of a DNS server.

Answer 2

It's possible for a DHCP server to assign the DNS and gateway IPs by itself. Depending on the setup of your network, it may not be necessary to input these addresses at all.

Answer 3

I guess leaving it void indicates (to the OS) that the router up (the ISP's router) serves as the gateway. And the OS adds this info to each packet automatically.

As to weather it prevents signals from an antenna, I wouldn't know.