1, router
(1), the router is a gateway to a LAN and the external network
(2), the entire Internet routers into one LAN and communicate with each other between the respective LAN.
(3), the router sub internal management (Local Area Network), may be provided in the router in the subnet segment, set the IP address of the wired port, DHCP function is provided, so the LAN is determined by the IP address of the router.
(4), the external networked routers, network depends on the external network (such as ADSL dial-up, broadband account, LAN, etc.). This time it corresponds to router node is one of the higher-level network only.
(5), the equivalent of two NIC router, a gateway to do internally, a done outside node.
(6) The main function of the router for each packet through the router to find a best path (route) and forwarded. In fact, the LAN computer to send data packets to the external network and external network reply to the LAN computer data packets.
(7), a network router technology is the most important technology, determines the stability and speed of the network.
2, DNS (Domain Name Service Domain Name Service)
(1), the online world of house number: IP address
(2), the IP address shortcomings: difficult to remember, is not intuitive
(3), IP address alternatives: the domain name, e.g. www.baidu.com
(4), DNS server is dedicated to providing conversion between domain names and IP address of the service, which is a domain name corresponds to an IP address, like a table, like, so the domain name is to be purchased
(5), we visit a website process is: first, using the IP address (such as Google's DNS server IP address is 8.8.8.8) access to the DNS server (DNS server can not be a domain name, can only be a direct IP address), check out our IP address of the domain name you want to access, and then use the IP address visit our website really want to visit. This process is a shielded encapsulated browser, which is used in the DNS protocol.
(6), the browser is the need for DNS services, and QQ such a client does not need (because QQ programming already know the IP address of the Tencent server, so you can directly access the server IP). That is why we are getting on the Internet browser, and QQ but they can board. Because, DNS problem arises.