Notes, summaries, assignments, exams, and exercises for Computer science for Primary education

Bridges and Switches: Essential Network Elements

Bridges (Puentes) and Switches are network elements that possess control capabilities, storing and forwarding the frames they receive through their ports based on their content.

They are primarily used to interconnect similar or different Local Area Networks (LANs). A bridge isolates traffic between network segments.

For instance, if an Ethernet network needs to exceed 2.5 km in length, a bridge can be installed to segment the network. By assigning each segment a length not exceeding 2.5 km, a total network length of up to 5 km can be achieved.

OSI Layer 2 Operation

Bridges operate at OSI Layer 2 (Data Link Layer). Their basic unit of operation is the frame.

Phases in Frame Pathing Between Segments:

Understanding the Internet: A Global Network

The Internet is a global network of interconnected computers that any device can join. It functions as a Wide Area Network (WAN), which is essentially a series of connected Local Area Networks (LANs).

Data packets are transmitted between computers using protocols that govern how information is sent and received.

Key Internet Technologies and Services

Technologies and services available over the Internet include:

• Web Pages: HTML documents presenting images, sound, and text, accessed via a web browser.
• Web Applications: Software accessed through a web browser.
• Native Applications: Applications developed for specific devices (e.g., smartphones), accessible without a browser.
• Email: Electronic mail communication.

Border Gateway Protocol (BGP)

BGP (Border Gateway Protocol) is a routing protocol used to exchange routing information between different networks or Autonomous Systems (AS) on the Internet. It is called an inter-domain routing protocol because it works between different networks.

Roles of BGP

• Connects different Autonomous Systems.
• Exchanges routing information between networks.
• Selects the best path for data transmission.
• Prevents routing loops.
• Maintains internet routing tables.

Example: When a user using Airtel internet accesses a Google server, BGP helps choose the best route between the Airtel network and the Google network.

CSMA/CD: Collision Detection in Ethernet

CSMA/CD stands for Carrier Sense Multiple Access with Collision Detection. It is a...

ADSL and DSL Technologies

ADSL (Asymmetric Digital Subscriber Line)

Advantages

• User: High-speed access, permanent connection, fast service provisioning.
• Telephone Company: Dual function of existing cable, no central office occupation, no risk of switched network collapse, service installed only on requested lines.

Disadvantages

• Service unavailability on certain lines (poor condition, distance from the central office).
• Potential for poor quality home cabling.
• Router cost.
• Requires a phone line.
• Cost in Spain.
• Theoretical limit for acceptable service at 5.5 km line length.

ADSL2+

Extends ADSL downstream capability with bit folding, achieving speeds of up to 24 Mbps downstream and 3.5 Mbps upstream. Doubles bandwidth from 1.1 MHz to 2.2 MHz.

ATM over ADSL

Allows...

1. Independent Set to Vertex Cover Reduction

Input

A graph G and an integer k.

Reduction Steps

1. Call the black-box for Vertex Cover with the input graph G.
2. Provide n-k as the target size, where n is the number of nodes in G.
3. Return the result ('yes' or 'no') from the black-box call.

2. SAT to Independent Set Reduction

Input

A CNF formula F.

Reduction Steps

1. Construct a graph G where the nodes of G are the literals occurring in F (with possible repetitions).
2. Add the following edges to G:
   • An edge joining every pair of complementary literals.
   • An edge joining any two literals that occur in the same clause.
3. Call the black-box for Independent Set with input graph G and an integer k, where k is the number of clauses in F.
4. Return the result ('yes' or 'no') from the

It permits traffic from wireless clients in 10.10.10 y 10.10.20The solution must have active PEFNG licensesHave Radius server send different roles for users in different departments.Apply role-based firewall policiesChange user to any in the user any svc-dhcp permit ruleClientMatchAirwave combines information from more sources, such as Radius authenticating servers and APsWireless security camera operating on channel 8To support more POE devices directly connected to the MCSet the VLANs associated with desired subnets in the WLAN settingsRADIUS serverAddition of custom rules to control access for authenticated guestsIt removes any commands that are not supported on that MC or have dependency errorsMesh Portal APChoose ClearPass or the other

1. Local Users and Roaming Profiles

Is it possible to assign local users roaming profiles on a Windows client integrated into a domain? Why?

No. Roaming profiles can only be assigned to users in Active Directory (i.e., domain global users). Local users can manage and use only local profiles on the machine where they are registered.

2. Storage for Roaming User Profiles

Where should roaming user profiles be stored?

On the server. The system stores a local copy of the domain profile, but the actual configuration of the elements customized by the user is always stored in the folder on the domain controller designed for this purpose.

3. The %username% Variable

What does the variable %username% represent and what replaces it?

It represents the username that...

Tarea 1: Registrar Kilometraje por Práctica Insertada

Requisito: Crear un TRIGGER donde, cada vez que se inserta una práctica a un alumno, se deben sumar 50 KMS al vehículo que tiene asignado el alumno.

Definición del Trigger PRAC (Inserción de Práctica)

CREATE TRIGGER PRAC
ON PRACTICA
FOR INSERT
AS
    DECLARE @CODMON INT;
    DECLARE @CODAL INT;

    -- 1. Obtener el ID del Monitor asignado al Alumno de la práctica insertada
    SELECT @CODAL = A.CodMon#
    FROM ALUMNO A
    INNER JOIN INSERTED I ON A.CodAl# = I.CodAl#;

    -- Nota: La siguiente selección es redundante o lógicamente incorrecta en este contexto:
    -- SELECT @CODMON = M.CodMon#
    -- FROM MONITOR M
    -- INNER JOIN ALUMNO A ON M.CodMon# = A.CodAl#
    -- WHERE M.

Redo Log File Management

The file system provides warnings when additional redo log groups are required. When a group is filled, a LOG FILE SWITCH event occurs. Control passes to the next group until the end of the sequence is reached, at which point the system returns to the first group and overwrites the data (acting as a circular buffer), potentially losing track of transactions.

Redo Log Files

The set of redo log files is known as the Redo Log of the database. Its primary function is to record all changes made to data. These files are critical for protecting the database against failures and are essential for recovery.

Groups and Members

• Groups: Redo log files operate in a sequence; one is active while the others wait. Each group has a unique

Master-Slave Flip-Flop Operation

The working of a Master-Slave flip-flop involves two cascaded flip-flops: a master and a slave. The master is positive level-triggered, and the slave is negative level-triggered, ensuring the master responds before the slave.

When the clock pulse (CP) goes high (1), the slave is isolated, allowing the J and K inputs to affect the master's state. The slave flip-flop remains isolated until the CP goes low (0). When the CP transitions back to low, information is passed from the master flip-flop to the slave, and the output is obtained.

Let's examine the behavior based on J and K inputs:

• J=0, K=1: The high Q' output of the master goes to the K input of the slave. The negative transition of the clock forces the slave