Static and Dynamic IP Addresses

 

There are two ways to configure a computer’s TCP/IP settings:

 

Server-assigned IP address —Provided by the DHCP server on the network

 

Static IP address —Assigned manually to each computer by editing the properties for thenetwork adapter

 

Table 2-4 compares the differences in these configurations.

		Chapter 2: Networking 47
Table 2-4 Static Versus Server-Assigned IP Addressing
Setting	What It Does	Static IP Address	Server-
			Assigned IP
IP address	Identifies computer on	Unique value for each	Automatically
	the network	computer	assigned by
			DHCP server
DNS	Identifies domain name	IP addresses of one or	Automatically
configuration	system servers	more DNS servers, host	assigned by server
		name, and domain name
		must be entered

 

Gateway Identifies IP address

 

of device that connects

 

computer to Internet or

 

other network

 

IP address for gateway Automatically

 

must be entered; same assigned by server

 

value for all computers on

 

network

 

 

DHCP

 

Dynamic Host Configuration Protocol (DHCP) server (which provides IP addresses automatically) is also used to provide the Domain Name System (DNS) servers and gateway device IP addresses. A DHCP server is typically built into small office/home office (SOHO) routers, cable modems, satellite modems, and digital subscriber line (DSL) modems.

 

Subnet Mask

 

A subnet mask is used to distinguish between the network portion of the IP address and the host portion. The subnet mask is also used to define subnetworks if subnetworking is being implement-ed (see Table 2-5).

 

Table 2-5 An IP Address and Corresponding Subnet Mask

IP Address/Subnet Mask	Network Portion	Host Portion
192.168.1.1	192.168.1
255.255.255.0	255.255.255

 

 

Gateway

 

A gateway is the IP address of the router or other device to which that PC is connected. It is the “gateway” to the rest of the World Wide Web.

 

To see the current IP address, gateway, and DNS information for your system, open a command prompt window and run the IPCONFIG.EXE program with the /all switch:

 

ipconfig /all

 

Refer to Figure 2-6 for a typical listing of information for a laptop with a wireless adapter.

48 CompTIA A+ Quick Reference

 

TCP and UDP Ports, Protocols, and Uses

 

Table 2-6 lists the most common networking protocols, their ports, and gives a brief description. The port numbers in Table 2-6 are used to set up firewall hardware or programs to permit traffic.