TIPS N TRICKS PARADIGM

OSI Model ( O pen  S ystems  I nterconnection model) The International Standards Organization's OSI model serves as a standard template for describing a network protocol stack. The Protocol Stack Using TCP/IP as a model, the sending application hands data to the transport layer, which breaks it up into the packets required by the network. It stores the sequence number and other data in its header. The network layer adds source and destination data in its header, and the data link layer adds station data in its header. On the other side, the corresponding layer reads and processes the headers and discards them. Upper Layers Layers 7 through 4 comprise the upper layers of the OSI protocol stack. They are more geared to the type of application than the lower layers, which are designed to move packets, no matter what they contain, from one place to another. Application Layer 7 This top layer defines the language and syntax that progra

IP address classes Class 1 st  Octet Decimal Range 1 st  Octet High Order Bits Network/Host ID (N=Network, H=Host) Default Subnet Mask Number of Networks Hosts per Network (Usable Addresses) A 1 – 126* 0 N.H.H.H 255.0.0.0 126 (2 7  – 2) 16,777,214 (2 24  – 2) B 128 – 191 10 N.N.H.H 255.255.0.0 16,382 (2 14  – 2) 65,534 (2 16  – 2) C 192 – 223 110 N.N.N.H 255.255.255.0 2,097,150 (2 21  – 2) 254 (2 8  – 2) D 224 – 239 1110 Reserved for Multicasting E 240 – 254 1111 Experimental; used for research Note:  Class A addresses 127.0.0.0 to 127.255.255.255 cannot be used and is reserved for loopback and diagnostic functions. Private IP Addresses Class Private Networks Subnet Mask Address Range A 10.0