Chapter 3

• MAC address


  48 bits, written as six hex numbers separated by colons, also called physical address
• IP address


  IPv4 addresses have 32 bits and are written as four decimal numbers called octets, IPv6 addresses have 128 bits and are written as eight blocks of hexadecimal numbers
• Port numbers


  Used at the transport layer
• Domain names


  Application layer, including FQDNs (Fully Qualified Domain Names)
• Configuring TCP/IP settings


  1. IP address

  2. Subnet mask

  3. Default gateway

  4. DNS servers
• MAC addresses


  • First 24 bits are the OUI (Organizationally Unique Identifier) or manufacturer-ID, last 24 bits are the extension identifier or device ID
• Static IP addresses


  Assigned manually by the network administrator
• Dynamic IP addresses


  Automatically assigned by a DHCP (Dynamic Host Configuration Protocol) server
• Gateway


  Device that nodes use for access to the outside world
• Subnet mask


  Used to indicate what portion of an IP address is the network portion (network ID) and what part is the host portion (host ID)
• DNS server


  Server responsible for tracking computer names and their IP addresses
• ipconfig utility


  Used in a Command Prompt to find out current TCP/IP settings
• IP address classes


  • Class A
  • Class B
  • Class C
  • Class D
  • Class E
• Class D IP addresses

  Begin with octets 224-239 and are used for multicasting
• Class E IP addresses

  Begin with octets 240-254 and are used for research
• Reserved IP addresses


  • 255.255.255.255
  • 0.0.0.0
  • 127.0.0.1 through 127.255.255.254
  • 169.254.0.1 through 169.254.255.254
• Network Address Translation (NAT)

  A technique designed to conserve public IP addresses needed by a network
• Address translation


  Process where a gateway device substitutes the private IP addresses with its own public address
• Port Address Translation (PAT)

  Process of assigning a TCP port number to each ongoing session between a local host and Internet host
• SNAT (Static (or Source) Network Address Translation)


  The gateway assigns the same public IP address to a host each time it makes a request to access the Internet
• DNAT (Dynamic Network Address Translation)


  The gateway has a pool of public address that it is free to assign to a local host when it makes a request to access the Internet
• IPv6 address


  128 bits written as eight blocks of hexadecimal numbers separated by colons
• Link (local link)


  Any LAN bounded by routers
• Dual stacked


  When a network is configured to use both IPv4 and IPv6
• Tunneling


  A method used by IPv6 to transport IPv6 packets through or over an IPv4 network
• Interface ID


  The last 64 bits or four blocks of an IPv6 address that identify the interface
• Neighbors


  Two or more nodes on the same link
• Types of IPv6 addresses

  • Unicast
  • Global unicast
  • Link local unicast
  • Multicast
  • Anycast
• IPv6 address prefixes


  • Global unicast: 2000::/3
  • Link local unicast: FE80::/64
  • Unique local unicast: FC00::/7, FD00::/8
  • Multicast: FF00::/8
• IPv6 auto configuration


  1. Computer creates link local IPv6 address using FE80::/64 prefix

  2. Checks if address is unique

  3. Asks router for configuration information
• IP address types


  • Global unicast
  • Link local unicast
  • Unique local unicast
  • Multicast
• Global unicast


  2000::/3, first 3 bits are always 001
• Link local unicast


  FE80::/64, first 64 bits are always 1111 1110 1000 0000 0000 0000 ... 0000
• Unique local unicast


  • FC00::/7, first 7 bits are always 1111 110
  • FD00::/8, first 8 bits are always 1111 1101
• Multicast


  FF00::/8, first 8 bits are always 1111 1111
• IPv6 address autoconfiguration


  1. Computer creates its IPv6 address using FE80::/64 as the first 64 bits

  2. Last 64 bits can be randomly generated or generated from the network adapter's MAC address

  3. Computer checks to make sure its IP address is unique on the network

  4. Computer asks if a router on the network can provide configuration information
• Port numbers


  Ensure data is transmitted to the correct process among multiple processes running on the computer
• Socket


  Consists of host's IP address and the port number of an application running on the host
• Port number types


  • Well-known ports (0 to 1023)
  • Registered ports (1024 to 49151)
  • Dynamic and private ports (49152 to 65535)
• Protocols not yet covered: TFTP, NTP, LDAP, SMB, SIP, H.323