What can get Tricky in the CCENT exam ?

1.Subnetting , like can there be a host with all 1's
   Example : 123.14.255.48
   subnetting .net and lammle.com  great sites for subnetting.


2.ACL .
            Like there is a long ACL and no permit ip any any
            at the end , which can be easily over looked.
            And the difference if ACL is applied incoming
            or outgoing.
            UDP or TCP Ports , UDP ports not to forget
            as some protocols use only UDP like SNMP
            DNS client uses UDP , if a host should not be
            allowed  to resolve URL.
            DHCP server client .
            ICMP options
            port range ,gt,lt etc
            INterVLAN ACL

3.show commands ,should be perfect.
   show ip route
   show ip ospf etc etc

4.Administrative distance and Metric in show commands.

5.Advertising a loopback interface.

6.Ping and interface from same router works only when keepalives
   flow or a host is connected there.

7.TCP UDP IP Header , OSI and TCP/IP Model , Cabling.
   Difference between TCP and UDP , UDP does not use sequence numbers.

8.enable secret and enable password options.Privilege levels.

9.OSPF cost,passive interface,router id.

    cost = 10^8/ BW

      BW : 1.T1 or DS1 = 1.544 Mbs
               2.T3 or DS3 = 45 Mbps
               3. 10BaseT =  10Mbps
               4. 100BaseT = 100Mbps
               5. 1000BaseT = 1000Mbps

10.Switch broadcast behaviour.
     Switch redundant links and multiple switches interconnected
     and a single switch port showing multiple interfaces.

11.Allowed VLAN's , Switching modes access,trunk,dynamic desirable,
    dynamic auto,no-negotiate.

12.switchport security ,err disabled,difference : protect, restrict and shutdown

13. runts ,giants ,crc etc

14.Ports can shut down if miss match in Bandwidth or Duplex
      at either ends.

15.Even Up/Down Interfaces are used in OSPF router-id election processes.

16. IPv6 stateless autoconfiguration and insertion of FFFE in the interface
      MAC and inversion of 7th bit.OSPFv3.

17.To check local TCP/IP stack ping 127.0.0.0 or 127.255.255.255
    will not work.

     127.0.0.1 to 127.255.255.254 will work.
     127.0.0.0 is Network number.
     127.255.255.254 is last host.
     This is a Network.

18.Private IP Addresses are not Routable on the Internet.
      Can be a trick question.

19.Remember we can Ping only what is listed in the Routing tables.
     show ip route on the router should light up the path to the network.