Datamaunz

Read More

Scenario small business 4 departments in 2 offices instead of purchasing 4 separate address ranges from the internet authorities, we buy one single range (less expensive): Class C 200.15.10.0/24 this range can be divided up further and be assigend to the different departments when subnetting, we take... Read More

Problem with IP Address Classes companies would receive class A (16,777,214 hosts), B (65,534 hosts) or C (254 hosts) classes depending on the number of hosts needed jumps between allocatable hosts within these classes are huge thus, huge amount of global address space was wasted solution: Classless Inter-Domain Routin... Read More

function on the same subnet, host can send traffic directly to each other to send traffic to a host on a different subnet, it must be forwarded by a router the subnet mask enables the host to understand, if the destination is on the same or a different subnet 32 bits long written in dotted or slash notation ... Read More

classes A, B, and C include all the addresses which are valid to be assigned to hosts what about 224.0.0.0 to 255.255.255.255? Class D addresses class D: reserved for IP multicast addresses the four high order bits in a class D address are set to binary 1 1 1 0 not allocated to hosts no default subnet mask ... Read More

Class B addresses class B: assigned to medium-sized to large-sized networks the two high order bits in a class B address are set to binary 1 0 default subnet mask is /16 valid network addresses range from 128.0.0.0 to 191.255.0.0/16 allows for 16,384 networks and 65,534 hosts per network in... Read More

subnet size tradeoff between # of networks and # of hosts the bigger the host portion of the network, the more hosts are possible but the fewer networks e.g., if the subnet mask is /8, 24 bits available to allocate hosts /24, 8 bits available to allocate hosts Idea behind internet addressing IANA (Internet Assi... Read More

notes are based on How to use VirtualBox (Beginners Guide) Installation go to www.virtualbox.org/ Read More

Overview 3 main IP traffic types unicast: to a single destination host to send to multiple hosts, separate copies of the same traffic have to be sent to each host individually broadcast: to all hosts on the subnet one copy of the traffic is sent everywhere throught part o... Read More

Function routing packets to their destination ensure Quality of Service one type of traffic might require better level of service than another e.g., voice or video more sensitve to delay; thus, we might give it priority over email Protocols IP (Internet Protocol): best known layer 3 protocol (focus here on IP... Read More

Fundamentals an IPv4 address is 32 bits long written as 4 octests in dotted decimal format for example: 192.168.10.15 each octet is 8 bits long: (4 x 8 = 32 ) # check ip on windows command prompt ipconfig # check ip on linux terminal ifconfig # get default gateway on linux terminal ip route # check ip in Cisco IOS enable ip in... Read More

Fundamentals computers work in binary electrical impulses are either off or on (two choices: 0 or 1) per column in a number, we have two possible choices: 0 or 1 every time a column is added to the left, its value is multiplied by 2 256 128 64 32 16 8 4 2 1 ... Read More

Function provides transparent transfer of data between hosts responsible for end-to-end error recovery and flow control Fundamental Terms flow control: process of adjusting the flow of data from the sender such that the receiving host can handle all of it metaphor: you speak slower if someone does not understand the langua... Read More

IOS Command Hierarchy ios is not case sensitive levels hostname>: User exec mode not that often used: limited set of commands that can be entered here ? shows all the commands that are available on this level Enter scrolls through line by line Space scrolls through page by page to ... Read More

Running vs. startup config config t # to go to global configruation mode hostname Router1 # the change from the previous name "Router" to "Router1" takes effect immediately in running config Running config: The config that is in effect right now Startup config: The config that will be in effect once the device is (re)booted as long as ch... Read More

Comparison to main protocol stack for computer operations TCP: Transmission Control Protocol IP: Internet Protocol OSI TCP/IP conceptual used to transfer data in production networks 7 layers documented 4 layers documented better to be referenced in conv... Read More

Console connection to router via cable Cisco devices tend to not have initial IP addresses we thus need to set one up (initial configuration) if we want to connect to them console connection: connect to the device on a lower level than IP (e.g. to do the initial configuration) connect to the console port on the router or switch... Read More

Example Office 1 Local Area Network [PC], [Server], [Server] -> switch Router Office 2 Local Area Network [PC], [Laptop] -> switch Router Office 1 <–> Production Network <–> Office 2 Assume you are at the PC in office 2 and you want to connect to the router in office 1 ... Read More

Basics Open Systems Interconnect Model ISO standard standardizes how computer communicate over a network 7-layered approach to data transmission operations are divided into related groups of actions at each layer a layer serves the layer above it Example Sending an email: Computer (sender) Switch Serv... Read More

Networking allow connectivity between different end hosts on the network Characteristics Topology how are the devices connected to each other? Example Office 1 Local Area Network [PC], [Server], [Printer], [Laptop -> wireless access point] -> switch Router Firewall Internet Office 2 Local Ar... Read More

Write the press release Update the website something else The world is flat. term definition X^2^ Here’s a sentence with a footnote. 1 I need to highlight these ==very important words==. H~2~O This is the footnote. ↩ Read More

Intro Big Data refers to data sets that are too complex for traditional data-processing software 3 Vs of Big Data Volume: Size of the data Variety: Different sources and formats Velocity: Speed of the data Concepts and Terminology Clustered computing: Collection of resources of multiple machines Parallel computing: Simultan... Read More

Most of the content (and all images if not specified differently) is taken from Introduction to Pyspark on DataCamp. What is Spark Why? Platform for cluster computing Spread data and computations over clusters with multiple nodes (each node can be thought of as a separate computer) As a consequence, data processing and computation are ... Read More

Intro These are notes from reading the documentation of PostgreSQL. Basics PostgreSQL uses a client/server model. A session consists of: a server process managing the database files, accepting connections to the database and performing database actions on behalf of clients. The server program is called postgres the user’s client app... Read More

Most of the content (and all images if not specified differently) is taken from Introduction to Airflow by Mike Metzger. General What are DAGs DAG: Directed Acyclic Graph Directed: inherent flow representing dependencies between components Acyclic: does not loop/cycle/repeat Graph: the set of components Within Airflow, DAGs are w... Read More

Great resource for joins Read More

Most of the content (and all images if not specified differently) are taken from Introduction to SQL by Nick Carchedi. SQL SQL stands for Structured Query Language It is a language for interacting with data stored in something called a relational database. A relational database can be thought of as a collection of tables. A table is j... Read More

Most of the content (and all images if not specified differently) are taken from Database Design by Lis Sulmont. Understand the requirements Questions worth asking Schemas: How should my data be logically organized? Normalization: Should my data have minimal dependency and redundancy? Views: What joins will be done most often? Access... Read More

Most of the content (and all images if not specified differently) is taken from Introduction to relational databases in SQL by Timo Grossenbacher. Prerequisites Introduction to SQL Relational Databases real-life entitites become tables reduced redundancy data integrity by relationships Inspecting PostgreSQL databases PostgreSQL ... Read More

The content is based on DataCamp’s Intro to Bash Scripting. Intro Bash stands for Bourne Again Shell Bash was developed in the 80’s. It is often the default in Unix systems and Macs. Unix is the backbone of the internet, which is why all mayor cloud providers have commandline interfaces to their products. Prerequisites: Understand wh... Read More

Resources This is a good guide to learn about the basic markdown syntax. Read More