Local area network (LAN) Interview Preparation Guide

Very simply, a WLAN is a wireless or radio frequency extension of a LAN. Some WLANs however, such as ad-hoc networks have no wired components. Generally these networks are based on the IEEE 802.11 protocol suite but can also consist of proprietary communication protocols.

YES! WLANs use much of the same technology (and even more in cases) that makes digital PCS phones secure. Spread spectrum and frequency hopping was originally developed for military use. The technology was designed to keep prying enemy ears from intercepting highly sensitive data. Both of these technologies are used in virtually all WLAN applications.

Besides making the radio link secure, the data is also encrypted for even more security if the radio link were ever ?tapped?. Different equipment manufacturers have implemented 40 bit, 64bit and 128 bit encryption. This initial attempt at security had some weaknesses, which were quickly identified.

New enhancements known as ?Wi-Fi Protected Access? (WPA) greatly improve the security of WLAN links. The two primary areas of improvements are in the areas of data encryption and user authentication.

The new encryption technique TKIP (Temporal Key Integrity Protocol) addresses all the known vulnerabilities of the previous WEP encryption technique by ?wrapping? a very secure protective layer over the existing WEP packets.

WEP had virtually no user authentication mechanism in it?s initial deployment. WPA coupled with another authentication technique EAP (Extensible Authentication Protocol) provides the mechanism for true authentication services. This not only authenticates the user at login, but also protects the user from accidentally joining an un-wanted rogue network, which may steal network credentials.

Additional layers of security can be supported through virtual private networks (VPN), radius servers, and other techniques.

Basically all that is needed is a transmitting device, which connects to the Internet and operates in one of the unlicensed frequency bands, and a receiver (typically a PCMCIA card), which connects to your computer. But it?s not that easy?

There are many current products that have been designed with specific uses in mind. Some are very simple, and others very sophisticated. It?s sort of like asking what kind of computer does someone need? Well it really depends on what it?s being used for. Is it processing large amounts of data, maybe just used for surfing the web, possibly holding top-secret information! It?s obvious that the type of job dictates the type of equipment needed. Are you confused yet? Don?t worry! LBA has the expertise to help you decide what is the right system for your business application.

All products that conform to IEEE 802.11 standards maintain some interoperability. Products that carry the Wi-Fi certification are tested to verify a base level of interoperability.

The next release of LANwriter will provide this facility of connecting to an Active Directory server on the network for user management.

Administration of all aspects of LANwriter is done via a web browser from within the LANwriter application itself.

Every user is required to have a valid login account before using LANwriter to write data. User validation is against the WindowsXP security database of the computer hosting LANwriter. Users are of different kinds and there are ascending levels of security privileges. For eg. Admins have full control while Normal users can only compile data writing jobs and write them only after Approvers give approval. All data is cataloged and optionally archived to a spare Disk Drive before being written. This can be referred to at anytime to find out what data was written by any particular user for any particular job.

LANwriter being a browser-based application can be accessed over the internet if the LANwriter host is published as a virtual server behind your firewall. However this accessibility is best used for approving jobs remotely rather than for creating jobs which requires actual bulk file transfer over the network and cannot be done through the browser.

We can absolutely have too many APs and this can actually be more troublesome than too few APs. When devices on the same channel are co-located without enough channel separation the result is wasted equipment and reduced performance.

LAN is a computer network that spans a relatively small area. Most LANs are confined to a single building or group of buildings. However, one LAN can be connected to other LANs over any distance via telephone lines and radio waves. A system of LANs connected in this way is called a wide-area network (WAN). Most LANs connect workstations and personal computers. Each node (individual computer) in a LAN has its own CPU with which it executes programs, but it also is able to access data and devices anywhere on the LAN. This means that many users can share expensive devices, such as laser printers, as well as data. Users can also use the LAN to communicate with each other, by sending e-mail or engaging in chat sessions.