Random Cisco based networking questions - CCNA - Part 5

Another half a dozen random networking questions for 2015 with a more routing protocol focus this time, 

enjoy :-).

1. Triggered updates (in a routing protocol) are used to speed the convergence process?

A) True
B) False

2. What class of routing protocol is EIGRP?

A) Link state
B) Distance vector
C) Hybrid

3. What is the administrative distance of OSPF?

A) 110
B) 1
C) 120
D) 90
E) 100

4. What command would you use to erase the startup config of a router?

A) erase nvram
B) erase flash
C) delete startup
D) erase startup
E) delete run

5. What is required for VTP to communicate VLAN information between switches?

A) VTP domain must be identical on all switches
B) One switch needs to be a VTP server
C) A router is required
D) Both A and B are correct
E) None of the above

6. What is the structure of the MAC address?

A) 32 bit network ID + 32 bit host ID
B) 14 bit vendor code + 6 bit serial number
C) 24 bit vendor code + 24 bit serial number
D) Network + Host

Searching for what type of nic card you have in your PC? The easiest way is with the MAC address ( not the kind shown below :-)

A great link you should bookmark for Vendor/Ethernet/Bluetooth MAC Address Lookup and Search at MACFIND.  This allows you to match your MAC address to its vendor or a vendor to a MAC - I find it very useful :-).

http://www.coffer.com/mac_find/

1.  Answer A

A triggered update is sent immediately in response to a change in the network (e.g. A link going down). The router detecting the change immediately sends an update message to its adjacent routers, which then generate their own triggered updates. This process continues until the network converges. Triggered updates occurs independently from the regular routing updates and are intended to speed the convergence process.

2. Answer C

EIGRP is a hybrid routing protocol which uses a combination of distance vector and link state methods to determine the best path. EIGRP is considered an advanced distance vector protocol because EIGRP sends out only incremental updates.

3. Answer A

Administrative distance is used by Cisco routers to select the best path when there are two or more different routes to the same destination from two different routing protocols. Administrative distance defines the reliability of a routing protocol.

Routing Protocol	Administrative distance
Directly connected interface	0
Static route out an interface	1
Static route to next-hop address	1
DMNR - Dynamic Mobile Network Routing	3
EIGRP summary route	5
External BGP	20
Internal EIGRP	90
IGRP	100
OSPF	110
IS-IS	115
Routing Information Protocol (RIP)	120
Exterior Gateway Protocol (EGP)	140
On Demand Routing (ODR)	160
External EIGRP	170
Internal BGP	200
Floating Static Route (ex. DHCP-learned)	254
Unknown	255

(Note : An AD of 255 will cause a router to dump this route from its table)

4. Answer D

To erase the startup configuration use the following command:

Router#erase startup-config, or
Router#erase startup

5. Answer D

VTP requires the following to communicate VLAN information between switches.  The VTP domain must be identical on all switches and one switch needs to be a VTP server.

6. Answer C

MAC Addresses are 48 bits long and consist of a 24 bit vendor code and a 24 bit serial number.

More coming, please leave comments if you find any errors or want to debate an answer :-)

Random Cisco based networking questions - CCNA - Part 4

Welcome to part 4 of the random networking questions (Cisco based) series.  This set has a few extra spanning tree questions with detailed explanations, have fun :-)


1. What is the default time Bridge Protocol Data Units (BPDUs)  are sent and received by switches?

A) 2 seconds
B) 10 seconds
C) 30 seconds
D) 60 seconds

2. What does the following statement do?

Switch(config-if)#spanning-tree portfast disable

A) Disables spanning-tree on the switch port
B) Disable spanning tree on the switch
C) Changes the spanning-tree switch to portfast mode

3. What determines network addresses (IP) when data link addresses (MAC) are known?

A) Ping
B) ICMP
C) ARP
D) RARP

4. The Cisco Spanning Tree protocol is compatible with IEEE 802.1d?

A) True
B) False

5. What type of switch port can belong to multiple VLANS?

A) Access port
B) Trunk port
C) Voice access port
D) No port can belong to multiple VLANs

6.What will be the IP address of the second subnet given the following?

172.16.0.0 255.255.224.0 (Assume ip subnet-zero is enabled)

A.) 172.16.0.0
B.) 172.16.8.0
C.) 172.16.16.0
D.) 172.16.32.0
E.) 172.16.64.0

Speaking of IP, I sometimes use a simple little site that gives you your own IP and other internet connectivity details   - IP Chicken - handy link  :-)

1. Answer A

http://en.wikipedia.org/wiki/Spanning_tree_protocol#Bridge_Protocol_Data_Units_.28BPDUs.29

Bridge Protocol Data Units (BPDUs) frames are sent out as multicast messages regularly at multicast destination MAC address 01:80:c2:00:00:00. When Bridge Protocol Data Units (BPDUs) are received, the Switch uses a mathematical formula called the Spanning Tree Algorithm (STA) to know when there is a Layer 2 Switch loop in network and determines which of the redundant ports needs to be shut down.

Three types of Bridge Protocol Data Units (BPDUs) are Configuration BPDU (CBPDU), Topology Change Notification (TCN) BPDU and Topology Change Notification Acknowledgment (TCA).

2.  Answer A

The time Spanning Tree Protocol (STP) takes to transition ports over to the Forwarding state can cause problems. PortFast is a Cisco network function which can be configured to resolve this problem by disabling STP from the switchport, thus making it come up quicker.

3. Answer D

Reverse Address Resolution Protocol (RARP) is used by a host computer to request its IPv4 address from an administrative host (DHCP server), it provides the server with its hardware address (MAC address).

http://en.wikipedia.org/wiki/Reverse_Address_Resolution_Protocol


NOTE: Dynamic Host Configuration Protocol (DHCP) is a client/server protocol that automatically provides an Internet Protocol (IP) host with its IP address and other related configuration information such as the subnet mask and default gateway.

4.  Answer B

The original Spanning-Tree protocol was created by Digital Equipment Corporation (DEC) which is now part of Compaq. The IEEE created its own version called IEEE 802.1d which is not compatible with the original version.

Cisco enhanced the original 802.1d specification with features such as Uplink Fast, Backbone Fast, and Port Fast to speed up the convergence time of a bridged network. However these new features are proprietary, and can only be configured on Cisco switches.

5. Answer B

Ethernet interfaces can be configured either as access ports or trunk ports. Trunks carry the traffic of multiple VLANs over a single link and allow you to extend VLANs across the network.

http://en.wikipedia.org/wiki/Virtual_LAN

6. Answer D 

The subnet block size is 256 - 224 = 32
The first subnet will be subnet zero 172.16.0.0
The second subnet will be 172.16.32.0

How did you go? I find a quick review of the questions and answers helps cement the basics and refresh the memory  - I hope these help, stay tuned for more...

The secret of life is not to do what you like but to like what you do.
By: Anonymous