Basic Questions 2

Question 1

Explanation

MDI stands for “Medium Dependent Interface”. MDI is a type of Ethernet port found on network devices. When connecting two devices with MDI ports (two hosts, for example) an Ethernet crossover cable is required. The crossover cable switches the send and receive ports on the two connectors, allowing data to flow correctly between two MDI ports.

Question 2

Explanation

Physical addresses or MAC addresses are used to identify devices at layer 2 -> A is correct.

MAC addresses are only used to communicate on the same network. To communicate on different network we have to use Layer 3 addresses (IP addresses) -> B is not correct; E is correct.

Layer 2 frame and Layer 3 packet can be recognized via headers. Layer 3 packet also contains physical address -> C is not correct.

On Ethernet, each frame has the same priority to transmit by default -> D is not correct.

All devices need a physical address to identify itself. If not, they can not communicate -> F is not correct.

Question 3

Question 4

Explanation

Only router can break up broadcast domains but in this exhibit no router is used so there is only 1 broadcast domain.

For your information, there are 7 collision domains in this exhibit (6 collision domains between hubs & switches + 1 collision between the two switches).

Question 5

Explanation

Use an Ethernet straight-through cable to connect an medium dependent interface (MDI) to an MDI-X port. Use a cross-over cable to connect an MDI to an MDI port, or an MDI-X to an MDI-X port.

Reference: https://www.cisco.com/c/en/us/td/docs/security/asa/hw/maintenance/5505guide/ASA5505HIG/pinouts.html

Note: MDI/MDIX is a type of Ethernet port connection using twisted pair cabling.

Question 6

Explanation

Verify that the TFTP or RCP server has IP connectivity to the router. If you cannot successfully ping between the TFTP or RCP server and the router, do one of the following:
– Configure a default gateway on the router.
– Make sure that the server and the router each have an IP address in the same network or subnet.

Reference: https://www.cisco.com/c/en/us/td/docs/routers/access/1900/software/configuration/guide/Software_Configuration/upgrade.html

The first option implies the router can be in a different subnet from the TFTP server -> D is not correct.

TFTP has no encryption process so answer B is correct.

Question 7

Explanation

At the end of each frame there is a Frame Check Sequence (FCS) field. FCS can be analyzed to determine if errors have occurred. FCS uses cyclic redundancy check (CRC) algorithm to detect errors in the transmitted frames. Before sending data, the sending host generates a CRC based on the header and data of that frame. When this frame arrives, the receiving host uses the same algorithm to generate its own CRC and compare them. If they do not match then a CRC error will occur.

The “Type/Length” field is used to indicate the “Type”of the payload (Layer 3 protocol) which is indicated as a Hexadecimal value.

Note: Ethernet II uses “Type” while the old Ethernet version use “Length”

Question 8

Question 9

Explanation

Single-mode fiber allows only one mode of light to propagate. Because of this, the number of light reflections created as the light passes through the core decreases, lowering attenuation and creating the ability for the signal to travel further. This application is typically used in long distance, higher bandwidth.

Because of the high dispersion and attenuation rate with multimode fiber cable, the quality of the signal is reduced over long distances.

Reference: https://www.multicominc.com/training/technical-resources/single-mode-vs-multi-mode-fiber-optic-cable/

In fact it is difficult to say what the maximum distance of single-mode or multimode fiber but according to this link (table 1):

https://www.cisco.com/c/en/us/products/collateral/interfaces-modules/gigabit-ethernet-gbic-sfp-modules/product_data_sheet0900aecd8033f885.html

Single-mode cable is good for installations longer than 10km.

At present, there are four kinds of multi-mode fibers: OM1, OM2, OM3 and OM4. The letters “OM” stand for optical multi-mode. OM3 and OM4 fibers will support upcoming 40 and 100 Gb/s speeds.