Assigning static IP and domain name mapping to local server in LAN

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http://serverfault.com – I have developed a web application which will be deployed in a LAN environemnt. Clients will be Computers/Android Tablets/IPAD In order for communication between client and local server 1) need to assign a static IP to local server. 2) need a domian name mapping for that IP address in Local environment. 3) router should assign the same static IP if it gets restarted etc. I am using a windows XP machine as Local server OS. Do i need to take care of router configurations before buying one, or all routers will have same capability to perform this task. I am not a network specialist, so Sorr (HowTos)