308(assig 5).pdf - ECSE 308 Assignment 5 Nusaiba Radi...

Info icon This preview shows pages 1–3. Sign up to view the full content.

ECSE 308 Nusaiba Radi Assignment 5 260672575 A. Review Questions 24.8. Give a brief description of DNS operation. The Domain Name System (DNS) is a general-purpose database for managing host information on the Internet. It supports any kind of data, including network address, ownership, and service configuration, to be associated with hierarchically structured names. It is primarily used to translate human-readable names of Internet resources to their corresponding IP addresses. 24.11. What is meant by saying that HTTP is a stateless protocol? It means that each transaction is treated independently. Accordingly, a typical implementation will create a new TCP connection between client and server for each transaction and then terminate the connection as soon as the transaction completes, although the specification does not dictate this one-to-one relationship between transaction and connection lifetimes. The stateless nature of HTTP is well suited to its typical application. 24.12. Explain the differences among HTTP proxy, gateway, and tunnel. Proxy: An intermediary program that acts as both a server and a client for the purpose of making requests on behalf of other clients. Requests are serviced internally or by passing them, with possible translation, on to other servers. A proxy must interpret and, if necessary, rewrite a request message before forwarding it. Proxies are often used as client-side portals through network firewalls and as helper applications for handling requests via protocols not implemented by the user agent. Gateway: A server that acts as an intermediary for some other server. Unlike a proxy, a gateway receives requests as if it were the original server for the requested resource; the requesting client may not be aware that it is communicating with a gateway. Gateways are often used as server-side portals through network firewalls and as protocol translators for access to resources stored on non-HTTP systems. Tunnel: An intermediary program that is acting as a blind relay between two connections. Once active, a tunnel is not considered a party to the HTTP communication, though the tunnel may have been initiated by an HTTP request. A tunnel ceases to exist when both ends of the relayed connections are closed. Tunnels are used when a portal is necessary, and the intermediary cannot, or should not, interpret the relayed communication.
Image of page 1

Info icon This preview has intentionally blurred sections. Sign up to view the full version.