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Module 08

Basic Network Configuration

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Objectives

Objective 2: Basic Network ConfigurationObjective 4: Configuring Client Side DNS

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Basic Network Configuration and Configuring Client Side DNS

Network InterfacesConfiguration files:

/etc/hosts: This file contains simple mappings between IP addresses and names and is used for name resolution

/etc/nsswitch.conf: This file controls the sources used by various system library lookup functions,such as name resolution.

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Basic Network Configuration and Configuring Client Side DNS

Network InterfacesConfiguration files:

/etc/resolv.conf: This file controls the client-side portions of the DNS system

/etc/networks: Like /etc/hosts, this file sets up equivalence between addresses and names, but here the addresses represent entire networks

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Basic Network Configuration and Configuring Client Side DNS

Network InterfacesConfiguration commands

ifconfig

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Basic Network Configuration and Configuring Client Side DNS

Network InterfacesConfiguration commands

ifconfig

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Basic Network Configuration and Configuring Client Side DNS

Network InterfacesConfiguration commands

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Basic Network Configuration and Configuring Client Side DNS

Network InterfacesConfiguration commands

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DHCP Configuration

DHCP handles IP address allocation in one of three ways:Dynamic allocation

DHCP server maintains a preset list of IP addresses designated by the system administrator.

IP addresses are assigned as clients request an address from the available addresses in the pool.

The address can be used, or leased, for a limited period of time. The client must continually renegotiate the lease with the server to maintain use of the address beyond the allotted period.

When the lease expires, the IP address is placed back into the pool for use by other requesting clients and a new IP address is assigned.

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DHCP Configuration

DHCP handles IP address allocation in one of three ways:Manual allocation

The system administrator may wish to designate specific IP addresses to specific network interfaces (for example, to an Ethernet MAC address) while still using DHCP to deliver the address to the client.

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DHCP Configuration

Subnets and relaysDHCP relay system can be established on subnets

without DHCP serversA relay system listens for DHCP client broadcasts,

forwards them to a DHCP server on another subnet, and returns DHCP traffic back to the client

Leaseswhen a client receives a dynamically assigned IP

address from a DHCP server, the address is said to be leased for a finite duration

The length of a DHCP lease is configurable by the system administrator

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DHCP Configuration

DhcpdThe DHCP server process is called dhcpd It is typically started at boot time and listens for incoming

DHCP request broadcastsdhcpd is configured using the text configuration file

/etc/dhcpd.conf