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.