CCNA small but usefull Notes 2

• Cisco Device boot sequence :
  1. POST
  2. Bootstrap
  3. Load IOS from flash to RAM
  4. Hardware Inventory
  5. Load Config file

• The SETUP that apears after starting a CISCO Router prompts for:

Hostname

Password & Secret

Router & Routing Protocols

IP Address

• CSMA/CA    is for 802.11 –> Wireless
• CSMA/CD    is for 802.3 —> Ethernet
• To check if SDM is installed in the router use this command    #show flash
• IPv6 works with DNS to track devices
• To go back to privileged there are 2 ways

ctrl+z

type #end

• To check interface’s security settings use this command #show port-security interface….
• To show Router’s memory STATs use #show memory
• To disable split horizon in an interface use  #no ip split-horizon in interface config mode
• Split-horizon only used bye Distance-vector protocols (RIPv1&2, IGRP, EIGRP)
• Copy config to TFTP  #copy run configuration tftp then follow by the IP , File name
• Copy from TFTP to FLASH of the Device use #copy tftp flash then follow the steps
• All routing protocols can load-balance across 4 equal-cost paths
• IGRP & EIGRP are the only protocols that can load-balance across unequal-cost paths
• To enable load-balance of unequal-cost paths in IGRP & EIGRP use command #variance in their config mode
• When choosing root bridge in spanning tree it always chooses the SW with the smallest priority 0 = always root,  61440= never root
• To change the priority use command #spanning-tree vlan .. priority .. for every VLAN
• To make the SW the root automatically  use command #spanning-tree vlan.. root primary
• To enable portfast on all non-trunking interfaces use command #spanning-tree portfast default
• To change the terminal History size use command  #terminal history … MAX size is 256
• CDP sends hello every 60 secs & the Hold time is 180 secs ( 3x Hello)
• When choosing DR in OSPF it always choose the Router with the highest priority if same priority then choose the highest Router ID (RID) through the highest loopback interface ip address, if no loopback then the highest ip address in physical interface
• To change the OSPF priority for an interface use command #ip ospf priority … in the interface config mode
• IPv6 Routing Protocols
  • EIGRP for IPv6
  • RIPng
  • MP_BGP4
  • OSPFv3

• VTP advertise every 5-mins or when change happens
• VTP advertisements are multicast
• In Store & forward mode in the SW the steps are
  • check CRC then discards frames smaller than 64-bytes and larger than 1518-bytes

• 802.1q trunking protocol adds 4-bytes TAG field to the frame
• ISL trunking protocol adds 30-bytes of info to the original frame (26-header, 4-trailer)
• VLAN range from 1-1005 & 1,1002,…,1005 are registered and cannot be deleted so the usable are from 2-1001
• The command  #show sessions is used to display telnets from the router
• The command  #show users is used to display telnet to the router & console connections
• To close active telnets use command #clear line … (VTY line Number)
• To turn CDP off in all interface used command #no cdp run
• To Turn CDP off on specific interface use command #interface ….. followed by command  #no cdp enable
• RIP max load-balance is 16 (default 4) and only equal-cost paths
• In ACL  0.0.0.0 255.255.255.255 is same as ANY
• Wild care masks are used by  OSPF and ACL
• The command #show protocol shows ROUTED protocol ( like IP )
• The Default Static Route begins with  #ip route 0.0.0.0 0.0.0.0 followed by next hope IP address (the ip address of the interface of the other router) or exit interface (the interface of the same router you are in)   as #ip route 0.0.0.0 0.0.0.0 fast ethernet 0/0
• In DHCP, Pool name is CASE SENSITIVE
• In spanning-tree, BPDUs are sent every 2-secs

that’s it for now, soon i will put other useful small notes that helps you in your revision…

~ by Network Techs. on September 2, 2009.