HPFOCUS

Understanding the TCP/IP Internet Layer

Internet Protocol Characteristics

Operates at network layer of OSI
Connectionless protocol
Packets treated independently
Hierarchical addressing
Best-effort delivery
No data-recovery features
Why IP Addresses?

They uniquely identify each device on an IP network.
Every host (computer, networking device, peripheral) must have a unique address.
Host ID:
-Identifies the individual host
-Is assigned by organizations to individual devices

IP PDU Header
IP Address Format: Dotted Decimal Notation

IP Address Classes: The First Octet
IP Address Ranges
Reserved Address
Public IP Addresses
Private IP Addresses

DHCP
DNS
-Application specified in the TCP/IP suite
-A way to translate human-readable names into IP addresses
Network Connection

IP network addresses consist of two parts: the network ID and the host ID.

IPv4 addresses have 32 bits that are divided into octets and are generally shown in dotted decimal form (for example, 192.168.54.18).

When written in a binary format, the first bit of a Class A address is always 0, the first 2 bits of a Class B address are always 10, and the first 3 bits of a Class C address are always 110.

Certain IP addresses (network and broadcast) are reserved and cannot be assigned to individual network devices.

Internet hosts require a unique, public IP address, but private hosts can have any valid private address that is unique within the private network.

DHCP is used to assign IP addresses automatically, and also to set TCP/IP stack configuration parameters such as the subnet mask, default router, and DNS servers.

DNS is an application that is specified in the TCP/IP suite, providing a means to translate human-readable names into IP addresses.

Host provides tools that can be used to verify the IP address of the host:
-Network connections
-IPCONFIG