ADVANTAGES AND DISADVANTAGES OF LAN & WAN

  Advantages: LAN
Low cost: Only need 2 computers connected together via a network card can become a Work group.
Easy configuration: the network configuration functionality built into the operating system windows
Easy to manage: Since this is a form of peer model, there is no management of any computer in the network.
Speed​​: The machine connected together via the internal network should be very high speeds.
Cons:
Distributed Data: Data sharing in LAN is stored locally on each computer in the network so if a machine is not turned on, the other machines can not navigate to the shared files on that machine is.
The safety and security is not high: The security and safety can peer through specifying the password for a certain resource, such as a shared folder on the network. Since all users in the peer network set up your own personal password system, and the sharing of resources can occur at any machine not happen in your focus, it is difficult to control focus . Moreover, the appearance of the virus spreads through the dangerous, if a machine can spread infection throughout the network, which will greatly impact to system maintenance.
No corporate governance and control users as well as manage the computers in the network.
LAN - File Server:
Advantages:LAN
Centralized management: data is stored centrally on the server, the folders are also to shared account access management server.
Increased security and data security in intranet.
Data transfer rate higher.
Cons:
Investment in Higher Costs due to server systems.
More complex governance: need for administrators to Maintain and manage networks.
Poor implacability: the number of accounts and a large number of computers will cause Difficulties in management.
The ability to Prevent attacks from the internet no less by the firewall system specific.

Advantages Of WAN

Covers a large geographical area so long distance businesses can connect on the one network
Shares software and resources with connecting workstations
Messages can be sent very quickly to anyone else on the network. These messages can have pictures, sounds, or data included with them (called attachments).
Expensive things (such as printers or phone lines to the internet) can be shared by all the computers on the network without having to buy a different peripheral for each computer.
Everyone on the network can use the same data. This avoids problems where some users may have older information than others.
Share information/files over a larger area
large network cover

Disadvantages Of WAN 

Are expensive and generally slow
Need a good firewall to restrict outsiders from entering and disrupting the network
Setting up a network can be an expensive and complicated experience. The bigger the network the more expensive it is.
Security is a real issue when many different people have the ability to use information from other computers. Protection against hackers and viruses adds more complexity and expense.
Once set up, maintaining a network is a full-time job which requires network supervisors and technicians to be employed.
Information may not meet local needs or interests

Vulnerable to hackers or other outside threats 

(RESOURCES):

http://www.answers.com/Q/What_are_the_advantages_and_disadvantages_of_a_WAN

https://sites.google.com/site/vandangcdth10/introduction/advantages-and-disadvantages