June 2004 Reader Challenge

The Problem:

All authors receive tons of mail from readers, asking questions, offering suggestions, and requesting support. Some of the mail I receive makes some interesting assumptions. Your challenge this month is to tell me what incorrect assumptions are in the two email questions I present here.

Reader Mail #1:
I added a hub to my network, and now the computers can't connect to the Internet. I think the hub is trying to distribute DHCP addresses to the computers, which already have an IP address assigned by my router. The computers are confused and don't know which IP address to present to the ISP to access the Internet.

Reader Mail #2:
I'm a security freak, and I want the tightest possible security for my network. My network is self-contained in one room. I'm planning to buy all wireless-G products instead of wireless-B and use Wi-Fi Protected Access (WPA). I'll use a wireless router to share my Internet connection through a cable modem. I was told that I have to buy an access point to have the security of infrastructure mode, instead of ad hoc mode. Is this true?

The Solution:

Reader Mail #1:
Hubs can't be DHCP servers. Your problem is likely with the router or the connections between the computers and the router. Your router is apparently failing to provide DHCP addresses. As a result, your computers are automatically using APIPA (i.e., private) IP addresses, which work only within the network. A computer with a private address can't access the Internet.

Reader Mail #2:
A wireless router has a built-in Access Point (AP), so you don't have to purchase another one. However, your concern for security prompts me to add that at the current time, wireless networks can't provide the level of security that a wired network can. With a wired LAN, an intruder would have to come to your building and plug into the LAN to access it, which is something you're rather likely to notice. A wireless network requires no such physical presence for an intruder.

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