Cisco Router CCNA Commands list you must know before you take CCNA exam, the list cover basic configuration, IPv4 and IPv6, Routing protocols like RIP and OSPF, DHCP and NAT.

Configure Basic Router Settings

Router# configure terminal
Router# hostname R1
R1(config)# enable secret class
R1(config)# line console 0
R1(config-line)# password cisco
R1(config-line)# login
R1(config-line)# logging synchronous
R1(config-line)# no exec-timeout
R1(config-line)# exit
R1(config)# line vty 0 4
R1(config-line)# password cisco
R1(config-line)# login
R1(config-line)# exit
R1(config)# service password-encryption
R1(config)# banner motd $ Authorized Access Only $
R1# copy running-config startup-config

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Configure an IPv4 Router Interface

R1(config)# interface gigabitethernet 0/0
R1(config-if)# description Link to LAN 1
R1(config-if)# ip address 192.168.10.1 255.255.255.0
R1(config-if)# no shutdown
R1(config-if)# exit
//configure interface s0/0/0
R1(config)# interface S 0/0/0
R1(config-if)# description Link to R2
R1(config-if)# ip address 209.165.200.225 255.255.255.252
R1(config-if)# clockrate 128000
R1(config-if)# no shutdown
R1(config-if)# exit
//configure interface loopback 0
R1(config)# interface loopback 0
R1(config-if)# ip address 10.0.0.1 255.255.255.0
R1(config-if)# exit

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Verify Interface Settings

//IPv4
R1# show ip route
R1# show ip route connected
R1# show interfaces
R1# show ip interface
R1# show ip interface brief
R1# show running-config interface g 0/0
//IPv6
R1# show ipv6 route
R1# show ipv6 routers
R1# show ipv6 interface brief
R1# show ipv6 interface gigabitethernet 0/0

R1# show running-config | section line vty
R1# show ip interface brief | include up
R1# show ip interface brief | exclude unassigned
R1# show ip interface brief | begin Gateway
R1# terminal length 20

R1# terminal history size 200
R1# show history

R1(config-if)# do show ip route | begin Gateway

---

Static Route

//IPv4
R1(config)# ip route 192.168.1.0 255.255.255.0 S0/0/0
R1(config)# ip route 192.168.1.0 255.255.255.0 192.168.1.2
R3(config)# ip route 172.31.0.0 255.255.255.0 s0/0/1 172.31.1.197
//floating static route
R4(config)# ip route 0.0.0.0 0.0.0.0 s0/0/1 5 

//IPv6
R1(config)# ipv6 unicast-routing
R1(config)# ipv6 route 2001:DB8:1:1::/64 Serial0/0/0
R1(config)# ipv6 route 2001:DB8:1:2::/64 2001:DB8:1:A001::2
R1(config)# ipv6 route ::/0 s0/0/0
R1(config)# ipv6 route ::/0 2001:DB8:ABAD:4::2

//Troubleshoot Static Route
R1# show ip route
R1# show ip route static
R1# show ip route 172.31.0.0
R1# show ip route connected

R1# show ipv6 route
R1# show ipv6 route static
R1# show ipv6 route 2001:DB8:ACAD:3::
R1# ping ipv6 2001:DB8:ACAD:3::1
R1# show running-config | section ipv6 route
R1# show ipv6 interface brief

---

-INTER-vLAN ROUTING

Configure
S1(config)# interface g0/0.10
S1(config-if)# ip address 172.17.10.1
S1(config-if)# encapsulation dot1q 10
S1(config)# interface g0/0.30
S1(config-if)# ip address 172.17.30.1
S1(config-if)# encapsulation dot1q 30
S1(config)# interface g0/0
S1(config-if)# no shutdown

-Dynamic Routing Protocols

-RIP Routing Information Protocol

Router(config)# Router RIP
Router(config-router)# version 2
Router(config-router)# network 192.168.1.0
Router(config-router)# network 192.168.2.0
Router(config-router)# passive-interface G0/0
Router(config-router)# passive-interface default

//disable
Router(config)# no Router RIP
Router(config-router)# no version
Router(config-router)# no network 192.168.1.0
Router(config-router)# no passive-interface G0/0

//IPv6
Router(config)# ipv6 unicast-routing
Router(config)# interface G0/0
Router(config-if)# ipv6 rip RIP-AS enable 

//Default Route
Router(config-router)# ip route 0.0.0.0 0.0.0.0 exit-intf next-hop-ip
Router(config-router)# default-information originate
Router(config-router)# ipv6 route 0::/0 2001:DB8:FEED:1::1
Router(config-router)# ipv6 rip RIP-AS default-information originate


//Troubleshooting RIP
Router# show ip protocols | begin Default
Router# show ip protocols RIP
Router# show ipv6 route
Router# show ipv6 protocols

-OSPF Open Short Path First

Router(config)# Router OSPF 123
Router(config-router)# router-id 10.10.10.10
Router# clear ip ospf process
Router(config-router)# network 172.16. 10.0 0.0.0.255 area 0
Router(config-router)# passive-interface default
Router(config-router)# passive-interface s0/0/0
Router(config-router)# no passive-interface s0/0/0
Router(config-router)# 
Router(config-router)# 

//Adjusting the Reference Bandwidth
Router# auto-cost reference-bandwidth 10000
//Adjusting the Interface Bandwidth 
Router(config-if)# bandwidth 64
//manually configure OSPF cost
Router(config-if)# no bandwidth 64
Router(config-if)# ip ospf cost 15625

//Configuring a Loopback Interface
Router# interface loopback 0
Router(config-if)# ip address 1.1.1.1 255.255.255.255


//Troubleshooting OSPF v2
Router# show ip ospf neighbor
Router# show ip ospf database
Router# show ip ospf interface
Router# show ip ospf interface brief
Router# show ip ospf interface serial 0/0/0
Router# show ip ospf interface serial 0/0/0 | include cost
Router# debug ip ospf packet
Router# show ip protocols
Router# show ip protocols | section Router ID
Router# show ip route
Router# show ip route 172.16.1.0
Router# show ip route | include 172.16.1.0
Router# show interface s0/0/0 | include BW

//IPv6
Router(config)# ipv6 unicast-routing
Router(config)# ipv6 router ospf 1
Router(config-router)# router-id 1.1.1.1

Router(config)# interface GigabitEthernet 0/0
Router(config-if)#ipv6 address 2001:db8:0:3::1/64
Router(config-if)# ipv6 ospf 1 area 0

Router(config)# clear ipv6 ospf process

//Troubleshooting OSPF v3
Router# show ipv6 ospf neighbor
Router# show ipv6 ospf database
Router# show ipv6 10
Router# show ipv6 route




//Default Route

ACL

//Configure
Router# interface Serial0/0/0
Router(config-if)# ip address 10.10.1.1 255.255.255.252
Router(config-if)# ip access-group 101 out

Router(config)# access-list 101 deny icmp any any echo
Router(config)# access-list 101 permit ip any any

R1(config)# no access-list 101 


//Troubleshooting
Router# show access-lists
Router# debug ip packet 101

DHCP

//Configure
Router(config)# ip dhcp pool LAN_DHCP_1
Router(dhcp-config)# network 10.10.10.1 255.255.255.0
Router(dhcp-config)# default-router 10.10.10.254
Router(dhcp-config)# dns-server 10.10.10.10
Router(dhcp-config)# netbios-name-server 10.10.10.111
Router(dhcp-config)# domain-name mattatech.com
Router(dhcp-config)# lease 14 12 23
Router(dhcp-config)# lease infinite

//Exclude IP Address range
Router(config)# ip dhcp excluded-address 10.10.10.10
Router(config)# ip dhcp excluded-address 10.10.10.10 10.10.10.20

//Enable/disable DHCP server and Relay agent
Router(config)# service dhcp
Router(config)# no service dhcp

//DHCP Relay
Router(config)# interface G0/0
Router(config-if)# ip helper-address 192.168.1.1

//Configure dhcp client
Router(config)# interface G0/0
Router(config-if)# ip address dhcp

//Troubleshooting
Router# show ip dhcp binding
Router# show ip dhcp binding 10.10.10.20
Router# show ip dhcp server statistics
Router# show ip dhcp conflict
Router# show ip dhcp database
Router# show running-config | section dhcp
Router# debug ip dhcp server events