L1-7 technologies, protocols, apps
L2 Forwarding 
ARP
MAC Addresses
Broadcast Domain
VLANs
  broadcast 
  Are VLANs required?
  When do I need a VLAN?
  Why not just subnet my network?
  How can devices on different VLAN’s communicate?
  What is a trunk port?  trunking protocols
  What do VLAN’s offer?
  Link aggregation
    To increase bandwidth
    to provide link failover
    LACP
Network Layer
  Understanding IP Addresses
    Classes
    Network Masks
    Understanding Subnetting /Math 
  Route Tables
  Routing Protocols
    static 
    Dynamic
      RIP 
      IGRP, EIGRP 
      OSPF 
      IS-IS
      BGP
  Why does fragmentation occur?
  How are the packets reassembled? at tcp udp L4
  TTL
  Packet Traversing
  IPv6
    types: 
      IPv4  unicast, broadcast and multicast.
      IPv6  unicast, multicast and anycast.
      
      2001:0db8:3c4d:0015:0000:0000:abcd:ef12
      2001:0db8:3c4d:0015:0:0:abcd:ef12
      2001:0db8:3c4d:0015::abcd:ef12
      
      0000:0000:0000:0000:0000:0000:192.168.1.25
      ::192.168.1.25
      
      0000:0000:0000:0000:0000:0000:0000:0001   localhost address
      ::1
Transport layer
  MTU
  MSS
  TCP
  UDP
  Protocol Ports
  TCP Timeout and Retransmission
  What are TCP RST Packets?
  TCP Options
  TCP Checksum
  TCP Error Correction
  Flow Control
  Congestion control
  Delayed Binding
  
Application layer
  HTTP Protocol
  HTTP versions: GET, POST, HEAD, OPTIONS, PUT, DELETE, TRACE and CONNECT
  Structure of HTTP Transactions
    A request line has three parts: a method name, the local path of the requested resource, version of HTTP,
                           example GET /           path/to/file/index.html                   HTTP/1.0
    The initial response line: the HTTP version, a response status code and an English reason phrase
                           example HTTP/1.0      200 OK                     or HTTP/1.0 404 Not Found
  status codes
  1xx indicates an informational message only
  2xx indicates success of some kind
    200 OK The request succeeded
  3xx redirects the client to another URL
    301 Moved Permanently
    302 Moved Temporarily
    303 Moved to another URL
    304 Not Modified
  4xx indicates an error on the client’s part 
    401 Authorization Required
    403 Forbidden The request was a valid request, but the server is refusing to respond to it.
    404 Not Found The requested resource doesn’t exist.
  5xx indicates an error on the server’s part
    500 Internal Server Error	  An unexpected server error.
    503 Service Unavailable  The server is currently unavailable
    
  The HEAD Method
    A HEAD request is just like a GET request, except it asks the server to return the response headers only,
  The POST Method
  HTTP Keep-alives
  HTTP Headers
  DNS
  SIP
  FTP, Active FTP vs. Passive
  SMTP 
  How HTTP Cookies Work? How do Web sites use cookies?
  URL