REDES

Suppose the content of a packet is the bit pattern 0011 1111 0100 0001 with odd parity scheme is being used. What would be the hexadecimal value of the containing the paruty bits if we use a two-dimensional scheme of 4 columns (fixing parity)?. 39. C6. 29. C5.

Suppose an entity sending the packet AB01 7317 93E4 that uses a check-summing method for error detection. What would be the hexadecimal value inserted in a frame to control errors caused during the transmisión?. B1FD. 4E03. B1FC. 4E02.

Which of the following services is not provided by the Link Layer?. Adjust the transmision and propagation times of the medium. Detect errors suffered by a frame during its transmisión. Avoid that a transmitting node excedes the processing capacity of a receptor node. Control who, when and how can transmit frames to the medium.

Which EDC technique allows you not only detecting but also correcting a single present in a frame?. Cyclic redundancy checks. Check-summing methods. Parity checks. None of above.

Trunck ports... Are tipically configured between hosts and switches. Can transport frames belonging to different VLANs. Are rarely used in current Ethernet LANs. None of the above is true.

The flow control techniques employ timers for: Detecting when a data frame is lost. Detecting when an ACK is lost. Detecting when a NACK is lost. All the previous answers are true.

Regarding the Stop-and-Wait Flow control technique, identify the true statement: The sender can send multiple frames at the same time. A NACK message acknowledges an erroneous/spurious received frame. This technique does not employ sequence numbers. All the aforementioned answers are false.

Looking at the figure below, what is the difference between the frames exchanged between JUNIPER AP1 and JUNIPER SWITCH 0 and the ones exchanged between JUNIPER AP1 and PC1. There is an extra link layer hardware address field on the Wireless Exchange. There is a need for a preamble on the Wireless Exchange that is NOT present at all on the wired Exchange. There is no difference because everything is ethernet. All the aforementioned answers are false.

Given the following network diagram describing the topology of a Local Area Network (LAN), identify the true statemet: A frame sent by PC1 to the broadcast address can collide with another frame sent by PC4. PC2 and PC5 depend on routing for communication. PC5 and PC7 belong to different broadcast domains. A frame sent by PC6 to the broadcast address is received by all PCs of the LAN.

Regarding the VLAN port assignation in a switch, identify the FALSE statement: Dynamic VLAN uses application layer identifiers. The port-to-VLAN table is employed in static VLAN assignation. The VLAN assigned to a port can vary in Dynamic VLAN assignation. Static VLAN is the most widely employed method.

Identify the true statement about switch interconnection when using VLANs: A port-to-VLAN table needs to be always configured in all switches. The VLAN trunking connection method has scalability problems. The port to port connection offers a scalable solution. VLAN trunking requires switches to support the IEEE 802.1Q standard.

If we need to create an Ad hoc and single-hop Wireless network, then: A wireless host will communicate with any other wireless station. We could use Bluetooth technology. It is necessary to configure a base station. All the previus answers are false.

The "Probe Request" frame defined in IEEE 802.11 is used: By an access point to announce a wireless network. By a wireless host to associate with an acces point. By access point to discover the presence of wireless hosts. By a wireless host to discover wireless networks.

The IEEE 802.11 technology (WiFi): Uses parity checks for error detection and correction. Uses a sliding-window scheme to implement flow control. Uses CSMA/CA to implement link access. All the aforementioned answers are true.

Consider the following Local Area Network consisting of an Ethernet switch and a WiFi acces poit: The PC1's MAC address, the PC2's MAC address and the AP's MAC address. The PC1's MAC address and PC2's MAC address. The AP's MAC address and PC2's MAC address. The PC1's MAC address and AP's MAC address.

IP is a network layer that guarantees: In-order packet delivery. Minimal bandwidth. Maximum jitter. None of the bove is true.

Which of the following fields of the IP header is used by a router to forward a packet?. Time-to-Live (TTL). Checksum. Source IP address. Destination IP address.

Suppose a host with the IP address 140.10.25.7/24. Identify the FALSE statement. The host belongs to the network 140.10.25.0. The host can have up to 256 neighbouring hosts connected to the same subnet. To communicate with all the neighboring hosts in the subnet, it can be used the 140.10.25.255 address. The network mask is 255.255.255.0.

Suppose you are assigned the 172.115.75.0/25 network IP address to créate the IP addressing scheme in a network infrastructure. We can affirm that: You have been assigned a class A network IP address. You have been assigned a class B network IP address. You have been assigned a class C network IP address. You have been assigned a classless network IP address.

A network administrator has the responsibility of creating the address space for a company consisting of several subnets. The design process must onsider the possibility that, in the future, new subnets can be created. Which of the following methods are advisable?. FLSM considering the number of subnets to be created. FLSM considering the subnet with the highest of hosts. VLSM. Answers b) and c) are correct.

Related to the host IP address, identify the FALSE statement: The host IP address of a computer dependds on the subnet where it is connected. The broadcast IP address is different for each subnet. A computer only accepts and processes packets destined to its host IP address. A computer can be uniquely identified in Internet by its public host IP adress.

When an IP packet is sent to a multicast IP address, then: The packet is destined to a host located an a private subnet. The packet uis destined to the host itself. A group of hosts located in different subnets will receive the packet. The resulting IP packet is invalid since multicast IP addresses are reserved for future use.

The host of a subnet configred with the network address 192.168.10.0/24 can access the public Internet as long as the network administrator configures: VLAN access port on the port on wich the host is connected to the switch. NAT and DNS in the host. NAT and DNS in the router. All the aforementioned mechanisms need to be configured.

ARP messages use as transport: Link-layer frames. Internet Protocol (IP). Transmission Control Protocol (TCP). User Datagram Protocol (UDP).

Assuming classless IP addressing if we perform a "ping” to the 192.9.44.70 address then the IP packet is sent... To a concrete host located in the 192.9.44.0 subnet. To all the host in the 192.9.44.0 subnet. To several hosts located in different subnets. We cannot answer properly the question without knowing the mask.

In routing table, default routers are configured using: Gateway = 0.0.0.0. Destination = 0.0.0.0. Mask = 0.0.0.0. Using both b) and c).

In a routing table... We can have several direct routes. We can have several default routes. We can have several routes to the same network. All of the aforementioned are correct.

What is FALSE about IPv6?. It has 128-bit addresses. Had security in mind as parto f its design. Does not support local communications. Eliminates the need for NAT.

Suppose the network configuration depicted in the following figure. The router uses NAT for the communication between the internal private network (192.168.1.0/24) and public Internet. Considering PC1 sends a packet to the web server with the following content, the packet received by the web server will contain: Source IP addr = 81.34.124.55 Source port = a new router's free random port. Source IP addr = 192.168.1.50 Source port = 6000. Source IP addr = 192.168.1.50 Source port = a new router's free random port. Source IP addr = 81.34.124.55 Source port = 6000.

Regarding TCP, say what is true: It does not resend missing chuncks. It does not have sequence numbers. It is considered a Transport Layer protocol. It provides the best speed and achieves maximum data transmisión rate.

Select what is FALSE about UDP: It is so simple thet it does not provide any error detection mechanism. It is so simple that its header has only 4 fields. There is a lenght fiel don the header. The header size is only 8 bytes.

What is true about TCP: The connection establishment is based on the three-way handshake consisting of Hello-Ack-Fin flags set in the header. The connection establishment is based on the three-way handshake consisting of three messages with flags set on SYN, SYN-ACK, ACK correspondingly. There is no need to have a special flag to finish the connection since any time a peer stops sending a tomeout is started. None of the aforementioned are true.

About the application layer say what is FALSE: Two posible architectures to follow while creating network applications are peer-to-peer and client-server. Application protocols are not standard in any case, therefore can not be defined in an RFC and belong to the company creating the application. Application processes communicate between each other employing sockets. None of the aforementioned is false.

Which of the following protocols are application layer protocols: TCP, UDP and SCTP. DNS, DHCP and HTTP. 802.11, 802.3 and 802.1Q. RSC, TESEDE and TE.

Which of the following are channel partitioning protocols?. TDMA, FDMA, CDMA. TDMA, FDMA, CDMA, CSMA. Aloha, CSMA, CSMA/CD. TDMA, FDMA, Aloha.

Which multiple access protocol allows each node to get the maximum link bandwidth?. CDMA. CSMA/CD. Token-passing. Polling.

Collisions caused by the end-to-end channel propagation are mitigated by: CSMA. CSMA/CD. Pure ALOHA. Slotted ALOHA.

Which os the following is not considered a technology suitable for deploying Personal Area Network?. RFID. NFC. LTE. Bluetooth.

Identify the true statement related to Ethernet technology: Flow control is not supported. Defines a generic frame also used in other IEEE 802 technologies. Error detection is base don check-summing method. Controls link access using the CSMA protocol.

Identify the false statement related to Ethernet frame format: It includes both the source and destination MAC address. The size of the transported datagram is limited. The "Type" field contains the network layer protocol to which the transported data belongs to. The "Preamble" is considered part of the frame and serves to wake up receiving network adapters.

According to the IEEE 802 reference model, error detection is implemented by the: Physical layer. Logical Link Control (LLC) sub-layer. Medium Access Control (MAC) sub-layer. The IEEE 802 model does not implement error detection.

Regarding the IP address and MAC addresses, which is the true statement?. The same public IP address can be used by two host connected to different subnets. The same public IP address can be used by two hosts connected to same subnet. Te same MAC address can be used by two hosts connected to different subnets. The same MAC address can be used by two hosts connected to same subnet.

A router has an IP packet of 2500 bytes that needs to be fragmented in order to send it through an Ethernet link. The router generates to fragments, where the size of the first one is the Uthernet MTU. What value must be assigned to the "offset" field of the second fragment?. offset = 0. offset = 25. offset = 185. offset = 185.

If we perform “ping” to the 127.0.0.1 address, then the IP packet is sent... To a multicast group. To a concrete host in the subnet. To all the hosts in the subnet. To the host itself.

Suppose a host is assigned the IP address 135.20.231.7 and the 255.255.176.0 mask. What is the network address to which the host belongs to?. 135.20.0.0. 135.20.231.0. 135.20.128.0. The mask is invalid, thus being imposible to calculate the network address.

Which of the following is not a valid IPv6 address?. 2001::4C1:1D4D. BABA:CAFE::. ED::42::78DB. D7AB:42:1::B15.