Basic Web Notions

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1- The traditional LAN architecture:

The following architectures are, or has been, used efficiently by the information networks and public enterprises.

  • The Ring Network: The ring topology, the hosts are connected one behind the other, forming a circle.
  • The Tree Network: The hierarchical topology is created the same way as the extended star topology. But, instead of linking together hubs and switches, the system is connected to a computer that controls the topology traffics.
  • The Mesh Network: This topology is used when you shouldn’t have any communication stop. Every host had its own connections to other hosts. This also represents one of the characteristics of Internet, that has multiple paths that leads to on emplacement.
  • The Bus Network: This topology consists of allowing all the hosts to be directly connected to one backbone segment.
  • The Star Network: All the cables are connected to a central point. This point is usually a hub or a switch.

2-Lists of navigation errors:

This list contains the majority of errors returned during a navigation (inaccessible page).

  • 301: Document permanently moved.
  • 302: Document temporarily moved, try again later.
  • 400: Bad request.
  • 401: Web Server (or page) non authorized, password required.
  • 402: Paying Server Access.
  • 403: Server not allowed (often FTP site).
  • 404: Server or File not found.
  • 407: Proxy authentication required.
  • 408: Connection timeout.
  • 409: Conflict
  • 414: File requested too long.
  • 500: Server Error
  • 501: Program missing
  • 502: Bad gateway
  • 503: Unavailable service
  • 504: Gateway is taking too much time to respond
  • 505: HTTP version unrecognized
  • 645: Problem configuring TCP/IP network.

3- Types of Ports:

Here are some TCP ports:

  • 0: Used by the DNS
  • 20: FTP data port, used for file transferring
  • 21: FTP control port
  • 22: SSH connection protocol, used for some applications that needs a remote connection
  • 23: Telnet
  • 25: SMTP, outgoing mail towards an SMTP server
  • 53: Domain Name Server (DNS), detects if the IP address is valid.
  • 68: Used for DHCP automatic configuration of IP addresses
  • 80: HTTP
  • 110: POP3 (Post Office Protocol) Inbout Mails
  • 137: NetBIOS Name Service, Activates the file sharing and printers in a local network, use this share via Intranet.
  • 138: NetBIOS
  • 139: NetBIOS
  • 143: Secure IMAP mail protocol 3
  • 220: Secure IMAP mail protocol 4
  • 443: Secure website navigation (HTTPS)
  • 445: NetBIOS, supplementary function implemented from Windows 2000 (no Millennium)
  • 1723: PPP Point To Point Protocol, used for VPN connections.