🧪 Lab: Your First Cisco Network

Tool: Cisco Packet Tracer (free with NetAcad account). GNS3 / CML also work — commands are identical.
Time: ~45 minutes.

Topology

 PC1 (192.168.1.10/24)                       PC2 (192.168.2.10/24)
        |                                          |
   [ Switch1 ]                                [ Switch2 ]
        |                                          |
   ----G0/0--- [ Router R1 ] ---G0/1----
   192.168.1.1                       192.168.2.1

Build it

1. Drag two 2960 switches, one 2911 router, two PCs onto the canvas.
2. Cable with copper straight-through:
   • PC1 ↔ Switch1 (Fa0 ↔ Fa0/1)
   • PC2 ↔ Switch2 (Fa0 ↔ Fa0/1)
   • Switch1 Fa0/2 ↔ R1 Gi0/0
   • Switch2 Fa0/2 ↔ R1 Gi0/1

Step 1 — Configure the PCs

Click PC1 → Desktop → IP Configuration:

IP Address:       192.168.1.10
Subnet Mask:      255.255.255.0
Default Gateway:  192.168.1.1

Repeat for PC2 with 192.168.2.10 and gateway 192.168.2.1.

Step 2 — Configure R1 (the CCNA core skill)

Click R1 → CLI tab → press Enter:

enable
configure terminal

hostname R1
no ip domain-lookup
enable secret Cisco123!

! ----- Console line -----
line console 0
 password ConPass!
 login
 logging synchronous
 exit

! ----- SSH setup -----
ip domain-name lab.local
crypto key generate rsa modulus 1024
username admin secret AdminPass!
line vty 0 4
 login local
 transport input ssh
 exit

service password-encryption

! ----- Interfaces -----
interface GigabitEthernet0/0
 description LAN-to-Switch1
 ip address 192.168.1.1 255.255.255.0
 no shutdown
 exit

interface GigabitEthernet0/1
 description LAN-to-Switch2
 ip address 192.168.2.1 255.255.255.0
 no shutdown
 exit

banner motd #Authorized access only!#

end
write memory          ! SAVE — without this you lose everything on reboot

Step 3 — Verify

From R1's CLI:

show ip interface brief    ! all interfaces — both should be up/up
show running-config        ! the live config
show ip route              ! routing table — should show two connected /24 routes
show version               ! IOS version, uptime, model

From PC1's Desktop → Command Prompt:

ping 192.168.1.1       # gateway — must work
ping 192.168.2.1       # router's far interface — must work
ping 192.168.2.10      # PC2 — the moment of truth
tracert 192.168.2.10   # should show 1 hop (R1) then PC2

🧯 Troubleshooting checklist

1. show ip interface brief — interface up/up?
2. Correct default gateway on the PC?
3. IPs in the same subnet as their gateway?
4. Forgot no shutdown?
5. Cable wired correctly? (green dots in PT)

🎁 Bonus challenges

1. Add a third LAN 192.168.3.0/24 on R1's loopback (interface loopback 0) and ping it from PC1.
2. SSH into R1 from PC2. Use admin / AdminPass!.
3. Use show mac address-table on Switch1 — see PC1's MAC learned dynamically.

❓ Module 1 Quiz

20 exam-style questions. Pick answers, hit Submit, get instant feedback with explanations. Score saves automatically.

🧠 Module 1 Cheatsheet

OSI (top → bottom)

7 App · 6 Pres · 5 Sess · 4 Trans · 3 Net · 2 DLL · 1 Phy
PDUs: Data → Segment → Packet → Frame → Bits

Powers of 2

2 4 8 16 32 64 128 256

Subnet masks

Magic number

MN = 256 − mask. Subnets jump by MN in the interesting octet.

RFC 1918 private ranges

10.0.0.0/8 · 172.16.0.0/12 · 192.168.0.0/16

Specials

127/8 loopback · 169.254/16 APIPA · 255.255.255.255 broadcast

Top ports

22 SSH · 23 Telnet · 25 SMTP · 53 DNS · 67/68 DHCP · 69 TFTP · 80 HTTP · 123 NTP · 161 SNMP · 443 HTTPS · 514 Syslog

IPv6

128 bits hex · :: collapses ONE zero run · fe80::/10 link-local · 2000::/3 global · ::1 loopback · ff00::/8 multicast

Essential router commands

enable
configure terminal
hostname X
interface gi0/0
 ip address A.B.C.D MASK
 no shutdown
end
copy running-config startup-config   ! save!
show ip interface brief
show running-config
show ip route