Networking, Ansible, Hosting Flashcards
(184 cards)
1
Q
What is Ansible?
A
A configuration management tool
2
Q
What must a computer do to visit a website?
A
Resolve the domain to a server, establish a secure connection, and download the web page.
3
Q
What is a protocol in networking?
A
A set of rules that define how two machines interact and exchange information.
4
Q
What are protocol stacks used for?
A
They organise protocols into layers, from physical transmission to complex data services.
- Low level protocols are used by higher level protocols to provide more complex services, such as reliable delivery of data across continents and secure communication.
5
Q
What are the two main protocol stacks?
A
TCP/IP and OSI.
6
Q
What does TCP/IP stand for?
What are the 4 stages?
A
Transmission Control Protocol/Internet Protocol.
- It’s the most widely used protocol stack, and is used in web browsers and networked devices.
- Application, transport, internet, physical
7
Q
What does OSI stand for?
What are the 7 stages?
A
Open Systems Interconnection.
- It’s a conceptual framework that provides a standardised way to understand and discuss network protocols and their interactions.
- Application, presentation, session, transport, network, data link, physical
8
Q
What are the three types of networking addresses?
A
- Domain Name: www.google.com
- IP Address: 192.168.1.3
- MAC Address: 3A ED 6C 4E B7 98
9
Q
Which OSI layer uses MAC addresses?
A
Layer 2: Data Link Layer - to allow NICs to talk to each other
10
Q
Which OSI layer uses IP addresses?
A
Layer 3: Network Layer
11
Q
What does the Physical Layer (Layer 1) do?
A
It transmits raw bits over a physical medium using signals. Concerned with:
- Converting bits into electrical/optical signals or wireless radio waves.
- Managing high voltages, timing and light pulses.
- Handling physical connectors and pin layouts.
12
Q
What is the Data Link Layer responsible for?
A
Communication between nearby devices and framing of data using MAC addresses.
- Communication in this layer uses ethernet.
13
Q
What device typically operates at the Data Link Layer?
A
Ethernet Switch (L2 Switch).
14
Q
What are the key fields in an Ethernet frame?
A
-Destination MAC: MAC address of receiver NIC
-Source MAC: MAC address of sender NIC
-Type: determines how payload is processed
-Data: contains encapsulated data
-CRC: Cyclic Redundancy check used for error detection
15
Q
What is the function of the Network Layer?
A
Responsible for logical addressing and routing data using IP (protocol)
16
Q
What does the Internet Protocol (IP) do?
A
Routes packets, assigns IP addresses, handles fragmentation and forwarding.
- provides a connectionless service so each packet is treated independently and can be transmitted over different network paths.
17
Q
What is the format of an IPv4 address?
A
Four decimal octets, e.g., 192.168.0.1
Four octets each represented by a decimal number ranging from 0 to 255. Some ranges of IPv4 addresses are set aside for private networks.
18
Q
What is the format of an IPv6 address?
A
Eight hexadecimal blocks, e.g., 2001:0DB8:ABCD:EF01:2345:6789:ABCD:EF01
- invented because we were running out of IPv4 addresses
- consist of eight hextets, each represented by a four-digit hexadecimal number.
19
Q
What does the Transport Layer ensure?
A
End-to-end communication, quality and reliability of data.
20
Q
What protocols operate at the Transport Layer?
A
- SSL (secure socket layer) and TLS (transport layer security) provide secure communication over networks through encrypting data.
- TCP provides reliable ordered and error checked delivery of data via IP networks.
- UDP provides unreliable communication, prioritises speed. Useful for time sensitive applications.
21
Q
When is UDP preferred over TCP?
A
For time-sensitive applications like video streaming or calls.
22
Q
What is the structure of an address with a port number?
A
IP address followed by a colon and port, e.g., 192.168.0.1:80.
23
Q
What do TLS and SSL do?
A
Secure communications through encryption and authentication.
24
Q
What replaced SSL and why?
A
TLS is an improved version, because SSL had security vulnerabilities
25
What are the four properties of a TLS connection?
1) Confidentiality: private connection created by encrypting data with a symmetric key
2) Encryption Negotiation: before data transmission, server and client agree encryption algorithm and keys to use.
3) Authentication: communication parties are verified using public key cryptography. Sever must always be authenticated.
4) Integrity: each message includes an integrity check, which prevents data loss or alteration
26
What is the TLS handshake?
A multi-step process that negotiates encryption and verifies server identity to start a secure session.
- involves the handshake procedure
27
What is a Certificate Authority (CA)?
A trusted entity that issues digital certificates to authenticate websites.
28
What does the Session Layer do?
Manages the creation, management and termination of sessions between applications.
29
What is the role of the Presentation Layer?
Translates data formats and handles encryption/decryption, compression and format conversion.
- ensures data sent by application layer of one system is readable by application layer of other system
30
What does the Application Layer provide?
provides services directly to end-users such as web browsing or email
common protocols: HTTP, DNS, SMTP.
31
What protocol is used for secure web browsing?
HTTPS (uses HTTP + TLS).
32
What are common HTTP methods?
GET, POST, PUT, DELETE, PATCH.
33
What does the GET method do?
Retrieves data without causing side effects.
34
What does the POST method do?
Submits data and may cause changes on the server.
35
What does the PUT method do?
Replaces the resource with the payload.
36
What does the DELETE method do?
Removes the specified resource.
37
What does the PATCH method do?
Applies partial updates to a resource.
38
What is the role of the NIC in networking?
The Network Interface Card (NIC) enables a device to connect to a network and communicate with other devices.
39
What is the purpose of the CRC in an Ethernet frame?
The Cyclic Redundancy Check (CRC) is used for error detection in data transmission.
40
How does the OSI model help in networking?
It provides a standardised framework to understand and design network systems by dividing them into seven layers.
41
What is the main function of routers in a network?
Routers direct data packets between different networks, operating at the Network Layer.
42
Why was IPv6 developed?
To address the exhaustion of IPv4 addresses by providing a vastly larger address space.
43
How does TLS ensure data integrity?
By using message authentication codes to detect any alterations during transmission.
44
What is the significance of port numbers in networking?
Port numbers identify specific applications or services on a device, allowing multiple services to run simultaneously.
45
What is the main idea behind the configuration as code approach?
It allows configuring servers and resources by writing code that defines their desired final state.
46
What types of computing resources can configuration as code be used with?
It can be used with servers, storage, and networking resources.
47
What is Ansible primarily used for?
Configuration management. Manages multiple machines organising them into an inventory
48
How does Ansible organise machines?
Into an inventory, which can be defined in formats like YAML or INI.
49
What is a core principle of Ansible’s architecture?
It is agentless — no persistent agents are needed on managed hosts.
50
How does Ansible communicate with managed hosts?
Ansible doesn’t require installing any persistent agent on the target nodes, instead communication with managed hosts happens over SSH (due to agentless architecture)
51
Does Ansible leave background processes running on managed nodes?
No, it only runs temporary modules which are removed after execution.
52
What protocol is commonly used to connect securely to remote computers?
- SSH (Secure Shell), a protocol for securely connecting to remote devices.
53
How do you connect to a remote server via SSH on Linux or Mac?
ssh username@remote_host
54
What tool can be used on Windows to connect via SSH?
PuTTY.
55
What command is used to SSH into a server?
ssh username@remote_host
56
How do you run an Ansible script from your machine?
Using the Ansible controller over SSH, without persistent agents on the nodes. Temporary modules are deployed and removed when tasks are complete.
57
What does the Ansible inventory track?
Host information.
58
What are the two types of Ansible inventory?
Static (text files) and dynamic (pulls info from external sources like cloud APIs).
59
What file formats can be used for Ansible inventory files?
YAML and INI.
60
What are playbooks in Ansible?
Files written in YAML that define desired configurations for host machines in a given inventory.
61
What are the four main steps when a playbook runs?
1. Connect to hosts via SSH. 2. Install and run required modules. 3. Modules communicate via JSON with ansible controller. 4. Modules are removed after execution.
62
What does idempotent mean in Ansible?
It makes only necessary changes; re-running a playbook doesn't cause repeated changes if not needed.
- If the system is already in the desired state, Ansible will not make any changes.
- allows safe re-runs of playbooks without worrying about unintended side effects
63
What is the purpose of the inventory file in Ansible?
To define the hosts Ansible will operate on.
64
What does 'ansible_connection: local' mean in a YAML inventory?
It tells Ansible to run tasks on the local machine, not over SSH.
65
What is the Ansible command to ping a group from inventory?
ansible -i hosts.ini local -m ping
-m specifies which module to use, in this case 'use the ping module'
66
What is the file format of an Ansible playbook?
YAML.
67
What does the ping module do in Ansible?
Checks if hosts are reachable.
68
How do you execute a playbook in Ansible?
ansible-playbook -i hosts.ini playbook.yml
69
What are Ansible plays?
Mappings of host groups to a set of tasks to execute.
70
Why do we say 'apache2 should be present' instead of 'install apache2' in Ansible?
Because Ansible is idempotent and will only install if it's not already present.
71
What does 'hosts' specify in a playbook?
The group of hosts the play applies to.
72
What does 'become: yes' do in Ansible?
It escalates privileges, similar to sudo.
73
What are tasks in Ansible?
Steps that define automation instructions using modules.
- Each task calls an Ansible module to perform some kind of operation.
74
What module installs packages in RHEL/Rocky?
ansible.builtin.yum
75
What module manages services in Ansible?
ansible.builtin.service
76
Can Ansible use custom modules?
Yes, in addition to hundreds of built-in modules.
77
What is the use of 'become' in Ansible?
To run tasks with root privileges.
78
How do conditionals work in Ansible?
Use a 'when' clause to apply a task only if a condition is true.
79
How is a 'when' clause written?
As a raw template expression, no double curly braces needed.
80
What keyword is used to capture the output of a task?
register
81
What module is used to print debug information?
debug
82
What syntax is used for variable interpolation?
{{ variable_name }}
83
What does 'loop: "{{ range(1, 4) | list }}"' do?
Loops over values 1, 2, and 3.
84
What does 'loop_control.label' do?
Specifies a label for each loop iteration.
85
Where can variables be defined in Ansible?
Inventory files, playbook files, and separate variable files.
86
What are facts in Ansible?
System information collected automatically about managed hosts.
87
What command shows facts collected by Ansible?
ansible -i hosts.ini local -m setup
88
What variable holds all gathered facts?
ansible_facts
89
How can you retrieve a specific fact in Ansible?
Use a playbook that references ansible_facts.
90
How do you run a playbook that requires sudo?
ansible-playbook -i hosts.ini user.yml --ask-become-pass
91
What is a web server?
A web server hosts and serves web content to users over the internet, handling requests and delivering web pages (HTML, JavaScript, CSS) to clients.
92
What is the most established web server?
Apache.
93
What tool is used to set up an Apache instance for serving HTTP/HTTPS content?
Docker.
94
How can security be enhanced when using web servers?
By hiding backend server IP addresses.
95
Describe the basic flow of a client request to a web server.
1) Client sends request to web server. 2) Web server processes request. 3) Web server sends response back to client.
96
What is a forward proxy?
An intermediary between a client and the internet that makes requests on the client's behalf.
- A request leaving the network will hit the proxy. The forward proxy sends on/makes the request on the client’s behalf.
97
List three use cases of forward proxies.
Caching, anonymising client requests, access control and content filtering.
98
Describe the basic flow through a forward proxy.
1) Client sends request to proxy. 2) Proxy forwards request. 3) Target server responds to proxy. 4) Proxy responds to client.
99
What is a reverse proxy?
A server that sits between the internet and web servers. Provides:
- Load balancing to distribute traffic across multiple servers
- Caching static content to improve response times
100
What is a popular reverse proxy used with Apache?
NGINX.
101
What tool is used to run NGINX and Apache together?
- Docker is used to create and run an NGINX instance which acts as a reverse proxy for our Apache instance.
102
Describe the basic flow through a reverse proxy.
1) Client sends request to reverse proxy. 2) Reverse proxy forwards to backend server. 3) Backend server responds. 4) Reverse proxy sends response to client.
103
Why do universities use forward proxies?
To manage bandwidth, ensure secure access, and control external website access.
104
List three benefits of using a forward proxy for a university intranet.
Improved performance, enhanced security and privacy, better policy compliance.
105
Why do e-commerce sites use reverse proxies?
To manage traffic, protect backend servers, and ensure high availability.
106
List three benefits of using a reverse proxy for an e-commerce site.
Improved performance, load balancing, enhanced security, increased reliability.
107
How does Apache handle requests?
Receives HTTP requests, processes them, and serves content (which can be static files) back to the client.
108
What does the Dockerfile for Apache do?
Starts from Apache image, copies HTML to document root, and exposes port 80.
109
How do you build a Docker image?
Use `docker build -t apache-image .`
110
How do you run a container from an image?
`docker run --name apache-container -p 8081:80 apache-image`
111
How do you access Apache’s config file?
`docker exec -it apache-container /bin/bash` then use `cat` or `docker cp`.
112
What does the DocumentRoot setting do?
Specifies the directory from which Apache serves files.
113
What is HTTPS and what does it require?
HTTPS is secure HTTP using TLS, which requires a certificate issued by a CA.
114
How do you generate a self-signed certificate using openssl?
`openssl req -x509 -nodes -days 365 -newkey rsa:2048 -out selfsigned.crt -keyout private.key -subj "/C=UK/ST=Merseyside/L=Liverpool/O=MyOrg/CN=www.example.com"`
Creates a certificate and private key for www.example.com openssl req is used to create a new private key and a self-signed certificate.
-x509 specifies that a self-signed certificate is to be generated.
-nodes prevents the encryption of the output key.
-days 365 sets the certificate to be valid for 365 days.
-newkey rsa:2048 creates a new RSA key of 2048 bits.
-out selfsigned.crt specifies the output filename of the certificate.
-keyout private.key specifies the output filename of the private key.
115
What does the -subj argument in openssl mean?
Specifies the subject name fields like country, state, locality, organisation, and common name.
116
What is `httpd-ssl.conf` used for?
It enables TLS/HTTPS in Apache by configuring SSL settings.
117
What does the Dockerfile’s COPY command do?
Copies files like index.html, selfsigned.crt, private.key, and httpd-ssl.conf into the container.
118
What does the sed command do in the Dockerfile?
- sed is a stream editor, used for modifying files programmatically from the command line. It’s a substitution command.
- This command searches for the commented ssl_module line and replaces it with an uncommented version, effectively enabling the module.
- The last sed argument is a file path, which specifies the file to modify - in this case,
- Uncomments configuration lines in httpd.conf to enable SSL modules.
119
How do you append the SSL config file to Apache’s main config?
Use `echo 'Include conf/extra/httpd-ssl.conf' >> /usr/local/apache2/conf/httpd.conf`
- The RUN echo ... command behaves as follows:
- The echo command is used to output the text Include conf/extra/httpd-ssl.conf.
120
What does the EXPOSE command do?
What ports does Apache expose for HTTP and HTTPS?
It informs cocker that the container listens on the specified network ports at runtime.
80 for HTTP, 443 for HTTPS.
121
How can we build the image and run an Apache SSL container?
docker build -t apache-ssl-image .
docker run --name apache-ssl-container -p 8081:80
-p 8082:443 apache-ssl-image
122
Why does the browser warn about self-signed certificates?
Because they’re not issued by a trusted CA. Browsers expect SSL/TLS certificates issues by a trusted CA.
123
When is it safe to proceed with a self-signed certificate warning?
In development or testing environments where you trust the source.
124
what are groupings?
They allow for selecting subsets of machines for specific tasks.
125
In the follow structure identify the components:
---
leafs:
hosts:
leaf01:
ansible_host: 10.16.10.11
leaf02:
ansible_host: 10.16.10.12
- leafs is a host group
- hosts starts the list of hosts for each group.
- leaf01, leaf02: defines the hosts in each group.
ansible_host: 10.16.10.11, specifies the IP addresses of the hosts.
126
What is a reverse proxy?
A server that receives client HTTP/HTTPS requests and forwards them to backend web servers.
127
Which server is configured as the reverse proxy in the setup?
NGINX
128
Which web server is being proxied by NGINX?
Apache HTTP Server
129
Command to create Docker network for communication:
docker network create web-net
- we create a custom NGINX config file to enable reverse proxying.
130
What does the directive 'upstream apache-server { server apache-container:80; }' do?
Defines a named set of backend servers for NGINX to proxy to.
131
What does 'listen 80;' mean in nginx.conf?
NGINX will listen for HTTP traffic on port 80.
132
Purpose of 'proxy_pass http://apache-server;'?
Tells NGINX to forward requests to the defined apache-server.
133
Command to build the custom NGINX image:
docker build -f Nginx.Dockerfile -t nginx-reverse-proxy .
134
Command to run Apache container in web-net:
docker run -d --name apache-container --network web-net apache-image
135
Command to run NGINX reverse proxy in web-net:
docker run -d --name nginx-proxy --network web-net -p 8083:80 nginx-reverse-proxy
136
How does traffic flow from client to Apache?
Client → NGINX on port 8083 → Apache over internal Docker network
137
What is Local Server Storage?
Storage on the server's physical hard drives with fast access times.
138
Why is local storage not ideal for cloud apps?
Because service data tied to a server is lost if the server fails.
139
What is NAS?
Network Attached Storage; shared storage with RAID config for redundancy, accessed as shared drives over the network.
Use NAS for Data centre storage to separate it from the compute servers.
140
Main disadvantage of NAS?
Single point of failure - one component failure can make all data inaccessible.
141
What is RAID?
Redundant Array of Independent Disks - a storage technology that combines multiple physical disks on the same server into one or more logical units for better redundancy and performance.
142
What is a SAN?
Storage Area Networks are specialised computer networks that store data.
- Consist of multiple disk arrays, switches and servers.
- an entire network over a single server stores data
- typically fibre optic can be copper to reduce cost.
143
Why have a SAN as a separate network?
It avoids performance impacts from compute network traffic.
- it's fault-tolerant because data is replicated across several disk arrays, so if anything goes down data can still be accessed.
144
What are relational databases?
Databases that store data in tables with unique keys and use SQL for querying.
145
What are popular relational databases?
MySQL and PostgreSQL
146
What command combines relational tables with shared columns?
JOIN
147
How do Graph Databases store data?
In nodes (entities) and edges (relationships) with attributes.
148
What is NoSQL?
Non-relational databases that handle unstructured data.
149
Examples of NoSQL databases?
MongoDB and Cassandra
150
Applications of graph databases in e-commerce?
Compute recommendations, perform fraud detection, supply chain analysis, and customer 360 view.
151
Popular graph database for e-commerce use?
Neo4j
152
Ways to use Neo4j?
- Neo4j Aura: A fully managed cloud service, which is free for small databases.
- Neo4j Desktop: A desktop application that allows you to run Neo4j locally.
- Docker: You can run Neo4j in a Docker container with the command:
153
Run Neo4j with Docker command?
docker run --name test-neo4j -p7474:7474 -p7687:7687 -d neo4j
154
what is neoj4's query language and what is the command to create a node?
CREATE (ee:Person {name: 'x', from: 'y', kloutScore: 5})
155
Cypher command to find a node?
MATCH (ee:Person) WHERE ee.name = 'x' RETURN ee
156
Cypher command to create multiple nodes and relationships?
CREATE (js:Person {...}), (ir:Person {...}), ...
157
Cypher command to find who Emil knows?
MATCH (ee:Person)-[:KNOWS]-(friends) WHERE ee.name = 'Emil' RETURN ee, friends
158
What is the cypher command to relate two person nodes:
CREATE
(js:Person { name: 'Johan', from: 'Sweden', learn: 'surfing' }),
(ir:Person { name: 'Ian', from: 'England', title: 'author' }),
(ee)-[:KNOWS {since: 2001}]->(js)
159
What is Ansible used for in cloud computing?
To configure large clusters of servers using Configuration as Code (CaC).
160
What are Ansible playbooks?
Files that specify the desired state of servers, which Ansible uses to configure them.
161
What does CaC stand for and what does it mean?
Configuration as Code; managing and provisioning system configurations through code.
162
What is the broader concept beyond CaC?
Everything as Code (EaC), which includes all parts of a system defined and managed as code.
163
What is Everything as a Service (EaaS)?
A model where cloud providers offer infrastructure, platforms, and software as services.
e.g. configuration, building and provisioning of servers can all be done as code.
164
How are variables defined in Ansible playbooks?
Where are they defined?
Using the 'vars:' keyword, e.g., vars: username: lisa
Ansible gathers facts about the hosts which can be used as variables.
Defined in dedicated variable files.
165
How can sensitive Ansible variables be secured?
By placing them in variable files encrypted using Ansible Vault.
166
What are group_vars and host_vars directories?
Directories for organising variables for specific groups or hosts in Ansible.
group_vars contains variables applied to specific groups of hosts.
host_vars contains variables applied to specific hosts.
167
What is variable interpolation syntax in Ansible?
{{ ... }}
It allows you to insert the value of a variable or expression into a string
168
What does Ansible Vault do?
Encrypts variable files to securely store sensitive information
such as Passwords, Private keys, config files.
- The data remains encrypted when stored on the host, and is decrypted only at runtime when Ansible playbooks need it
169
How is a hashed secure password created in Ansible?
Using the password_hash filter with an algorithm like sha512.
Example: password_hash('sha512'): Applies the SHA-512 hashing algorithm.
170
What does '--ask-vault-pass' do in Ansible?
Prompts the user for the Vault password to decrypt encrypted files.
171
What is Infrastructure as Code (IaC)?
Managing and provisioning infrastructure, using code.
IaC assumes that you have BareMetal (physical machines) or hypervisors (to spin up VMs).
172
What are the benefits of CaC?
Consistency, version control, repeatability, and automated testing of configurations.
- avoids undocumented, ad-hoc configuration changes by maintaining configurations in a version controlled repository.
173
How does IaC differ from CaC?
IaC manages infrastructure setup, while CaC handles configuration of that infrastructure.
174
What is a declarative approach in IaC/CaC?
Defining the desired system state, letting tools determine how to achieve it.
keeps a track of the current system state (simplifies management)
175
What is an imperative approach in IaC/CaC?
Specifying step-by-step instructions to achieve the desired system state.
176
What are the benefits of IaC?
Cost reduction, faster deployments, reduced errors, consistent infrastructure, scalability.
- they ensure the same environment is provisioned every time
- infrastructure can be dividied into modules and combined in different ways
- no manual provision needed, easier to manage
177
What tools can be used for IaC?
Tools like Terraform and Ansible.
178
What is IaaS?
Infrastructure as a Service: provides fundamental IT resources like servers and storage, and networking features, can be software or hardware.
Offers highest flexibility and management over resources.
179
What is PaaS?
Platform as a Service: provides platforms for application development without managing infrastructure.
Allows for focus on deployment/management of applications. Kubernetes is PaaS.
Removes concerns about resource procurement, capacity planning, software maintenance, patching, etc..
180
What is SaaS?
Software as a Service: delivers ready-to-use applications managed by the provider.
- In most cases, when people refer to SaaS, they are referring to end-user applications such as Gmail or Microsoft Office Online.
181
What is XaaS?
Anything as a Service: encompasses IaaS, PaaS, SaaS and more.
182
How do you create a vault encrypted file?
$ansible-vault create secret.yml
New Vault password:
Confirm New Vault password:
After creating a password, vault creates the secret.yml file and opens it in a text editor in the terminal. Then enter a username and passwd.
This is stored in the encrypted file, which is accessed in the playbooks
183
What does $ sudo grep list /etc/shadow do?
verify that a user has been created with the secret password as follows
output:
[sudo] password for dom:
lost:***:19795:0:99999:7:::
184
Anything as a Service (XaaS) : What are the 3 levels cloud providers offer wrt access to the cloud?
- IaaS (servers, networking, storage)
- PaaS (platform and environment to allow for building applications and services e.g. Gmail)
-SaaS (end user has a completed product that is run and managed by service provider)
