📘 CCNA 200-301 v1.1

1.10 Verify IP parameters for Client OS (Windows, Mac OS, Linux)

Learning Goal for the Exam

You must understand:

• How to view and verify IP configuration on Windows, macOS, and Linux.
• What information to look for: IP address, subnet mask, default gateway, DNS servers, MAC address.
• The commands or tools used in each OS.
• How to identify common issues (like missing IP address, wrong gateway, or DNS problems).

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🧠 Key IP Parameters You Must Verify

Every client device connected to a network needs some basic IP information.
When verifying, make sure these parameters are correct:

Parameter	Description	Example
IP Address	Unique address assigned to the client device. Used for identification on the network.	192.168.1.10
Subnet Mask	Defines which part of the IP address is the network and which part is the host.	255.255.255.0
Default Gateway	IP address of the router that forwards traffic to other networks (like the internet).	192.168.1.1
DNS Server	Resolves domain names (like cisco.com) into IP addresses.	8.8.8.8
MAC Address	Unique physical address of the network interface card.	00-1A-2B-3C-4D-5E

When one of these values is wrong, communication may fail — for example, you can’t access another subnet if your gateway is incorrect.

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💻 1. Verify IP Parameters in Windows

Windows provides both a Graphical User Interface (GUI) and a Command Line Interface (CLI) to view IP settings.

🪟 Using the Command Prompt (CLI)

This is the most important method for the CCNA exam.

✅ Command:

ipconfig /all

📋 Output Includes:

• IPv4 Address
• Subnet Mask
• Default Gateway
• DNS Servers
• MAC Address (listed as “Physical Address”)

🧩 Example Output:

Ethernet adapter Ethernet0:
   Connection-specific DNS Suffix  . : example.local
   Description . . . . . . . . . . . : Intel(R) Ethernet Connection
   Physical Address. . . . . . . . . : 00-1A-2B-3C-4D-5E
   DHCP Enabled. . . . . . . . . . . : Yes
   IPv4 Address. . . . . . . . . . . : 192.168.1.10
   Subnet Mask . . . . . . . . . . . : 255.255.255.0
   Default Gateway . . . . . . . . . : 192.168.1.1
   DNS Servers . . . . . . . . . . . : 8.8.8.8

🧾 Important Notes:

• If you see an IP like 169.254.x.x, it means the client failed to get an IP from the DHCP server (it’s using an APIPA address).
• Check if DHCP is enabled (for automatic IP assignment).
• Make sure Default Gateway and DNS Server are reachable.

🪟 Using GUI (for completeness)

1. Open Control Panel → Network and Sharing Center → Change adapter settings
2. Right-click on your active network adapter → Status → Details
3. You will see IPv4, subnet mask, gateway, DNS, and MAC address.

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🍏 2. Verify IP Parameters in macOS

You can use both GUI (System Preferences) and Terminal commands.

🖥️ Using Terminal

✅ Command:

ifconfig

This displays all network interfaces and their details.

You will typically look for:

• inet → IP Address
• netmask → Subnet Mask
• broadcast → Broadcast Address
• ether → MAC Address

Example:

en0: flags=8863<UP,BROADCAST,SMART,RUNNING,SIMPLEX,MULTICAST> mtu 1500
   ether 00:1a:2b:3c:4d:5e 
   inet 192.168.1.20 netmask 0xffffff00 broadcast 192.168.1.255

To check the default gateway (router):

netstat -rn | grep default

or

route -n get default

To check DNS servers:

scutil --dns

🧾 Important Notes:

• macOS uses 0xffffff00 as hexadecimal for subnet mask (equivalent to 255.255.255.0).
• Always verify that your interface (like en0) has an IP assigned and the gateway is reachable.

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🐧 3. Verify IP Parameters in Linux

Linux has several distributions (like Ubuntu, CentOS, Red Hat), but the commands are mostly the same.

🖥️ Using the Terminal (CLI)

✅ Command:

ip addr show

or the short form:

ip a

This command shows:

• Interface names (eth0, ens33, etc.)
• IPv4/IPv6 addresses
• MAC address

🧩 Example Output:

2: ens33: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500
   link/ether 00:1a:2b:3c:4d:5e brd ff:ff:ff:ff:ff:ff
   inet 192.168.1.30/24 brd 192.168.1.255 scope global dynamic ens33

To check default gateway:

ip route show

Example output:

default via 192.168.1.1 dev ens33
192.168.1.0/24 dev ens33 proto kernel scope link src 192.168.1.30

To check DNS servers:

cat /etc/resolv.conf

Output might show:

nameserver 8.8.8.8

🧾 Important Notes:

• /etc/resolv.conf file contains DNS server entries.
• ip command replaces older ifconfig and route commands.
• Make sure interface state is UP and not DOWN.

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⚙️ Quick Summary Table

OS	IP Config Command	Gateway Check	DNS Check	MAC Check
Windows	ipconfig /all	In same output	In same output	Physical Address in same output
macOS	ifconfig	netstat -rn or route -n get default	scutil --dns	ifconfig under “ether”
Linux	ip addr show	ip route show	cat /etc/resolv.conf	ip link show

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🧩 Troubleshooting Tips

Issue	Cause	Verification
No IP address / APIPA (169.254.x.x)	DHCP server not reachable	Check DHCP setting and connectivity
Wrong subnet mask	Device can’t reach local network properly	Verify correct mask
Wrong default gateway	Can’t access outside local network	Use ping to test gateway
Wrong DNS	Websites not resolving	Check DNS IP or test with nslookup

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🧠 Exam Pointers (for CCNA 200-301)

✅ You must memorize the main verification commands:

• ipconfig /all (Windows)
• ifconfig + netstat -rn (macOS)
• ip addr show + ip route show (Linux)

✅ Know what information to verify in the command output:

• IP address
• Subnet mask
• Default gateway
• DNS server
• MAC address

✅ Understand what 169.254.x.x means (Automatic Private IP Address / APIPA).

✅ Be able to identify configuration errors from command outputs.

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🏁 In Summary

Verifying IP parameters means checking if a client system’s network settings are correct so that it can communicate in the network.

• Windows: ipconfig /all
• macOS: ifconfig, netstat -rn, scutil --dns
• Linux: ip addr show, ip route show, cat /etc/resolv.conf

In all systems, confirm that the:

MAC address identifies the correct interface.

IP address matches the network,

Subnet mask is correct,

Default gateway leads to the router,

DNS servers resolve names correctly,

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