Troubleshooting and the Future of Networking

Error detection
The ability for a protocol pr program to determine that something went wrong
Error-recovery
The ability for a protocol or program to attempt to fix it
Errors still pop-up
miscounfiguring occur
Hardware breaks down
System incompatibilities come to light
The cloud
IPv6

The payload of ran ICMP packet exists entirely so that the recipient of the message knows which of their transmission caused the error being reported
Ping
Ping lets you send a special type of ICMP message called an Echo Request
If the destination is up and running and able to communicate on the network, it’ll send back an ICMP Echo Reply message type

A utility that lets you discover the path between two nodes, and gives you information about each hop along the way

An ISP almost always gives you access to a recursive name server as part of the service it provides.

DNS as A Service
Public DNS Servers
Name servers specifically set up so that anyone can use then, for free
Level 3 Communications
Most public DNS servers are available through anycast
Always make sure the name server is run by a reputable company, and try to use the name servers provided by your ISP outside of troubleshooting scenarios.

Registrar
An organization responsible for assigning individual domain names to other organizations or individual

The original way that numbered network addresses were correlated with words was through hosts files.

Hosts File
A flat file that contains, on each line, a network address followed by the host name it can be referred to as
1.2.3.4 webserver
Loopback address
A way of sending network traffic to yourself
127.0.0.1
Almost every hosts file in existence will, in the very least, contain a line that reads 127.0.0.1 localhost, most likely followed by ::1 localhost, where ::1 is the loopback address for IPv6
Hosts files are a popular way for computer viruses to disrupt and redirect user’s traffic.

Cloud Computing A technological approach where computing resources are provisioned in a shareable way, so that lots of users get what they need, when they need it
Hardware virtualization
Virtualization
A single physical machine, called a host, could run many individual virtual instances, called guests
Hypervisor
a piece of software that runs and manages virtual machines, while also offering these guests a virtual operating platform that’s indistinguishable from actual hardware
Public Cloud A large cluster of machines run by another company
Private cloud
Used by a single large corporation and generally hosted on its own premises
Hybrid Cloud
A term used to describe situations where companies might run things like their most sensitive proprietary yechnologies on a private cloud, while entrusting their less-sensitive servers to a public-cloud
Cloud Computing
A new model in computing where large clusters of machines let us use the total resources available in a better way

X as a service
Infrastructure as a service(IaaS) You shouldn’t have to worry about building youe own network of your own server
PaaS
SaaS
Platform as a Service(PaaS) A subset of cloud computing where a platform is provided for customers to run their services
software as a Service(SaaS) A way of licensing the use of software to others while keeping that software centrally hosted and managed
Gmail for Business
Office 365 Outlook

IPv6
IPv5 was an experimental protocol that introduced the concept of connections
IPv6 = 32 bits
IPv6 = 128 bits
Undecillion
Multicast
a way of addressing groups of hosts all at once
FF00:: multicast
FE80:: Link-local unicast
Link-local unicast addresses Allow for local network segment communications and are configured based upon upon host’s MAC address

Version field
A 4-bit field that defines what version of IP is in use
Traffic Class field
An 8-bit field that defined the type of traffic contained within the IP datagram, and allows for different classes of traffic to receivce different priorities
flow label field
A 20-bit field that’s used in routers to make decisions about the quality of service level for a specific datagram
payload length field
A 16-bit field that defines how long the data payload section of the datagram is
Next header field A unque concept to IPv6, needs a little extra explanation
Hop limit field
An 8-bit field that’s identical in purpose to the TTL field in an IPv6 header

IPv4 mapped address space
IPv6 tunnels servers take incoming IPv6 traffic and encapsulate it within traditional IPv4 datagram
IPv6 tunnel broker Companies that provide IPv6 tunneling endpoints for you, so you don’t have to introduce additional equipment to your network