IP Addressing
Classes of IP Addresses:
Reserved IP Addresses:
| Address | What it represents | Where can it be used |
|---|---|---|
| Network address of all 0s |
Stands for “this network”. For example, 0.0.0.120 |
Send a broadcast message to the network. |
| Network address of all 1s |
Represents “all networks”. |
Send a broadcast message to all networks. |
| Node address of all 0s |
Represents a network address or all hosts on a network. Example 10.0.0.0 or 172.16.0.0 |
Routers route traffic based on network addresses. |
| Node address of all 1s |
It represents all hosts on the network and is also called the broadcast address. Example 172.16.255.255 or 192.168.10.255 |
Used to send broadcasts to all hosts on the network. |
| Entire address of 0s |
Stands for “any network”. |
Used by routers to set a default route. |
| Entire IP set to all 1s. |
Stands for all hosts in network. |
Used to deliver/broadcast messages |
| 127.0.0.1 |
Stands for loopback address which is essentially the host itself |
Send traffic from the host to itself. Use this address in your browser to connect to the web server running on the host itself. |
Valid Hosts Addresses in Each Subnet:
| Network Address | Valid Host addresses | Broadcast Address |
|---|---|---|
| 192.168.10.0 | 192.168.10.1 – 30 | 192.168.10.31 |
| 192.168.10.32 | 192.168.10.33 – 62 | 192.168.10.63 |
| 192.168.10.64 | 192.168.10.65 – 94 | 192.168.10.95 |
| 192.168.10.96 | 192.168.10.97 – 126 | 192.168.10.127 |
| 192.168.10.128 | 192.168.10.129 – 158 | 192.168.10.159 |
| 192.168.10.160 | 192.168.10.161 – 190 | 192.168.10.191 |
| 192.168.10.192 | 192.168.10.193 – 222 | 192.168.10.223 |
| 192.168.10.224 | 192.168.10.225 – 254 | 192.168.10.255 |
Variable Length Subnet Mask (VLSM):
Troubleshooting IP Addressing:
| Troubleshooting | Description |
|---|---|
| Packet Internet Grouper (PING) |
Ping is one of the most commonly used utilities for troubleshooting addressing and connectivity problems. This utility is available for most operating systems, including Cisco devices, and can be accessed through the command line interface using the ping command. Checks if the target host is up using the ICMP protocol. |
| Traceroute |
Traceroute is another popular utility available on all operating systems. On some operating systems, the utility can be accessed using the tracert or traceroute commands in the CLI. It is used to find each hop between a source host and a destination host, helping to see the path taken by a packet. |
| IP config |
On Windows machines, all this information is displayed in the output of the ipconfig /all command. On Unix-based systems, this information can be viewed using the ifconfig command. |
| ARP Tables |
This table contains the MAC and IP address associations learned by the system. On most operating systems, the ARP table can be viewed with the arp –a command. On Cisco devices, you can view the arp table using the show ip arp command. |
CCNA Cheatsheet
A CCNA certification proves you have the competencies needed to navigate an ever-changing IT landscape. CCNA exams cover network fundamentals, IP services, security fundamentals, automation, and programmability. Designed for agility and versatility, CCNA proves you have the skills needed to manage and optimize today’s most advanced networks. CCNA training courses and exams are the foundation for advancing your career in any direction. A Cisco certification is living proof of the standards and rigor your organization recognizes and trusts to meet and exceed market demands. Here is a cheat sheet for CCNA Examination.