Cisco® CCDA Exam Notes : Access List,Spanning Tree Protocol(STP)

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CCDA certification is a foundation exam for testing Cisco network design fundamentals for the small office/home office (SOHO) market. CCDA certified professionals could design routed and switched networks involving LAN, WAN, and dial up access for small businesses.The exam is of 2 hours duration and there will be approximately 65 questions. Many questions are scenario based. Click here to visit official Cisco website to know more about this certification. CCDA is a pre-requisite for CCDP (Cisco Certified Design Professional) certification offered by Cisco Systems.

40. Cisco uses TFTP protocol to distribute IOS over a WAN link.

41. It is important to know the difference between a collision domain and a broadcast domain. When you use Hubs, all the nodes connected to the hub will be in the same collision domain. However, when you use switches and implement VLANs, each VLAN will be in a separate broadcast domain. The packet forwarding between VLANs is achieved through the use of routing.

42. IP routing protocols can load balance across up to six equal cost parallel links. The "maximum-paths" command can be used to change the number of links that the router will have to load-balance over IP.

42. Practice your demonstration before final demonstration to the customer.

43. Access Lists:

  • IP access list should be created with the ACCESS-LIST command. After the list is created, it can be applied to an interface with the IP ACCESS-GROUP command.
  • When applying access-lists, on a given interface, there can be only one access list per protocol for inbound. Similarly, there can be only one access list per protocol for outbound.

An example to remove an access list from an interface:

  • Int s0
  • No access-group 10

44. Spanning Tree Protocol (STP) 802.1d is used to prevent routing loops. In Cisco Catalyst 5000 series switches, use BDPUs (Bridge Protocol Data Units) to determine the spanning tree topology. STP uses a Tree Algorithm (STA) to prevent loops, resulting in a stable network topology.

45. IPX address consists of 32-bit network address and 48-bit host address. The network portion of the address is configured by the administrator. The host part of the address is the 48-bit MAC address on the network interface card of the node.

46. ISL, 802.1Q are the VLAN trunking protocols associated with Fast Ethernet. The VLAN trunking protocol defined by 802.10 is associated with FDDI. LANE (LAN Emulation) is associated with ATM.

47. Compression algorithms supported by Cisco IOS are:

  • HDLC - STAC;
  • LAPB - STAC, Predictor;
  • PPP - STAC, Predictor, MPPC
  • Frame-Relay - STAC, FRF.9

PPP is supported by STAC, Predictor, and MPPC. Compression algorithms supported by Frame-Relay for payload compression are STAC, and FRF.9.

48. Data Link Switching (DLSw) was introduced by IBM to overcome the limitations of SRB networks. The Cisco implementation of DLSw is called DLSw+. Benefits of DLSW+ are over SRB are:

  • Link layer acknowledgements and keep-alive messages of SNA do not have to travel over WAN link,
  • DLSw+ traffic can be rerouted in case of link failures
  • Prioritization of traffic over WAN links

49. The permitted numbers for some important access-lists are:

  • 1-99: IP standard access list
  • 100-199 :IP extended access list
  • 600-699: AppleTalk Access list
  • 800-899 : IPX standard access list
  • 900-999 : IPX extended access list
  • 1000-1099: IPX SAP access list
  • 1100-1199: Extended 48-bit MAC address access list

The format for standard IPX access list is:

access-list {number} {permit/ deny} {source} {destination}

50. By giving the command "show ip route igrp", we ca see the routes found by igrp. A route discovered by igrp is denoted by letter "I" before start of the entry.

51. 7 steps in building a Prototype are:

  • Review the customer's requirement
  • Determine the extent of the prototype
  • Understand your competition
  • Develop a test plan
  • Purchase and prepare equipment
  • Practice
  • Conduct final tests and demonstrations

52. Default administrative distances are as below:

  • Route Source--Default Distance
  • Directly connect Interface--0
  • Static Route--1
  • EIGRP Summary Route--5
  • Internal EIGRP--90
  • IGRP--100
  • OSPF--110
  • RIP--120
  • Unknown--255

The administrative distance (metric) is used to represent the trustworthiness of the route. Lower the value, higher the trustworthiness. A value of 255 represents that the route is unreachable.

53. Private addresses are described in RFC 1918. There are one Class A network, 16 Class B networks and 255 Class C networks that belong to private address space. There are:

  • Class Type---- Start Address----Stop Address
  • Class A ---- ----
  • Class B ---- ----
  • Class C ---- ----

54. Cisco IOS supports

  • Priority Queuing is useful for time sensitive, mission critical protocols such as SNA.
  • Custom queuing handles the queues in round robin fashion.
  • Weight Fair Queuing is enabled by default and requires no configuration.

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