# Glossary
This glossary puts in relation networking terms and Marfeel caching infrastructure. Reach out to add more definitions!
# Apex
A domain apex is the "root" level of your domain. For example, let's say you just purchased examplebrand.com. We'd call that the "domain apex", meaning that examplebrand.com is the "root" of the hierarchy of domain names. Notice in this example, the www.examplebrand.com domain is not apex.
# A record
An A record maps a domain name to the IP address (Version 4) of the computer hosting the domain. An A record is used to find the IP address of a computer connected to the internet from a name.
Click here to see an example:
As a result of a dig command to marfeel.com we can see it's A records pointing to the different IP adresses.
; <<>> DiG 9.10.6 <<>> marfeel.com
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 61837
;; flags: qr rd ra; QUERY: 1, ANSWER: 4, AUTHORITY: 0, ADDITIONAL: 1
;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 512
;; QUESTION SECTION:
;marfeel.com. IN A
;; ANSWER SECTION:
marfeel.com. 60 IN A 151.101.130.207
marfeel.com. 60 IN A 151.101.2.207
marfeel.com. 60 IN A 151.101.66.207
marfeel.com. 60 IN A 151.101.194.207
;; Query time: 21 msec
;; SERVER: 212.231.6.7#53(212.231.6.7)
;; WHEN: Wed May 06 17:28:34 CEST 2020
;; MSG SIZE rcvd: 104
For more information, check this link. (opens new window)
# CAA Record
DNS Certification Authority Authorization (CAA) is an Internet security policy mechanism that allows domain name holders to indicate to certificate authorities whether they are authorized to issue digital certificates for a particular domain name.
A CAA record is used to specify which certificate authorities (CAs) are allowed to issue certificates for a domain.
At Marfeel CAA records are recommended for CDN activation and when used, they must include globalsign.com. Read more about potential CAA issues.
# Cache
In computing, a cache is a hardware or software component that stores data so that future requests for that data can be served faster; the data stored in a cache might be the result of an earlier computation or a copy of data stored elsewhere. A cache hit occurs when the requested data can be found in a cache, while a cache miss occurs when it cannot.
- Caching headers (opens new window): Additional information the client and server can pass along with an HTTP request or response. For example, in Marfeel we add the
x-mrf-lastmodheader with information about the last time content was modified. - Purge: To permanently delete data, in this context a purge of all caching systems will force a refresh on the content since this will have to be taken from origin. Within Marfeel, µSmint purges the caching systems to ensure all content is fresh.
# Canonical name (CNAME)
CNAME records can be used to alias one name to another.
A common example is when you have both example.com and www.example.com pointing to the same application and hosted by the same server. In this case, to avoid maintaining two different records, it’s common to create:
- An A record for example.com pointing to the server IP address
- A CNAME record for www.example.com pointing to example.com
WARNING
A canonical link (<link rel="canonical" href="$SO) in the HTML is required for amp compatibility. (opens new window)
Click here to see an example:
As a result of a dig command to vanitatis.elconfidencial.com we can see the CNAME's trace, ending in the A record which points to the actual IP address.
; <<>> DiG 9.10.6 <<>> vanitatis.elconfidencial.com
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 14709
;; flags: qr rd ra; QUERY: 1, ANSWER: 3, AUTHORITY: 0, ADDITIONAL: 1
;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 512
;; QUESTION SECTION:
;vanitatis.elconfidencial.com. IN A
;; ANSWER SECTION:
vanitatis.elconfidencial.com. 60 IN CNAME cdn1s_incap1.titania.es.
cdn1s_incap1.titania.es. 14 IN CNAME cs916.wpc.edgecastcdn.net.
cs916.wpc.edgecastcdn.net. 3467 IN A 152.195.132.59
;; Query time: 21 msec
;; SERVER: 212.231.6.7#53(212.231.6.7)
;; WHEN: Wed May 06 17:34:07 CEST 2020
;; MSG SIZE rcvd: 149
Find in depth information on this cname record article. (opens new window)
# CDN
A CDN, short for Content Delivery Network, is a system of distributed servers that deliver pages and other Web content to a user, based on the geographic locations of the user, the origin of the webpage and the content delivery server.
# DNS
The Domain Name System (DNS) is the phonebook of the Internet. Humans access information online through domain names, like nytimes.com or espn.com. Web browsers interact through Internet Protocol (IP) addresses. DNS translates domain names to IP addresses so browsers can load Internet resources.
For more information, check this article. (opens new window)
# Domain name
A domain name is an identification string that defines a realm of administrative autonomy, authority or control within the Internet.
Domain names are used to identify one or more IP addresses. For example, the domain name marfeel.com represents several IP addresses.
Click here to see an example:
As a result of a dig command to marfeel.com (dig marfeel.com) we can see the IP adresses this domain is pointing to.
; <<>> DiG 9.10.6 <<>> marfeel.com
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 61837
;; flags: qr rd ra; QUERY: 1, ANSWER: 4, AUTHORITY: 0, ADDITIONAL: 1
;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 512
;; QUESTION SECTION:
;marfeel.com. IN A
;; ANSWER SECTION:
marfeel.com. 60 IN A 151.101.130.207
marfeel.com. 60 IN A 151.101.2.207
marfeel.com. 60 IN A 151.101.66.207
marfeel.com. 60 IN A 151.101.194.207
;; Query time: 21 msec
;; SERVER: 212.231.6.7#53(212.231.6.7)
;; WHEN: Wed May 06 17:28:34 CEST 2020
;; MSG SIZE rcvd: 104
For more information, check this link. (opens new window)
# Edge server
An edge server is the cache server that is geographically closest to the user. Its purpose is to cache content nearby the final user to serve much quicker than if it had to be delivered from an origin server (which can be anywhere in the world).
In Marfeel, we refer to edge servers as those that are the last layer of cache.
Example
If a user in Portland wants to read a site from London, and that site uses a CDN, that user gets the content from a PoP in Seattle instead of the request having to go to the origin server in London and traveling all the way back to Portland.
# Firewall
A firewall is a system that filters network traffic. It can either let it pass or block it, according to some specified rules. For example, it can block incoming connections aimed at a certain port or outgoing connections to a certain IP address.
For more information, check this link (opens new window).
TIP
A Firewall can be configured with MarfeelCDN active. Read more about firewalls and WAF servers and MarfeelCDN.
# HTTP
Hypertext Transfer Protocol (HTTP) is an application-layer protocol for transmitting hypermedia documents, such as HTML. It was designed for communication between web browsers and web servers, but it can also be used for other purposes. HTTP follows a classical client-server model, with a client opening a connection to make a request, then waiting until it receives a response.
All details about HTTP here (opens new window).
The "https" scheme (as in "https://marfeel.com") indicates that a resource is transported using the HTTP protocol, but over a secure TLS channel (opens new window).
# Origin server
The purpose of an origin server is to process and respond to incoming requests from Internet clients. The concept of an origin server is typically used in conjunction with the concept of an edge server or caching server. At its core, an origin server is a computer running one or more programs that are designed to listen for and process incoming Internet requests. An origin server can take on all the responsibility of serving up the content for an Internet property such as a website, provided that the traffic does not extend beyond what the server is capable of processing and latency is not a primary concern.
The origin server is where Marfeel extracts content from. Under origin.example.com you can find the exact IP or load-balancer dns where Gutenberg requests pages.
For more information about origin servers, check this link. (opens new window)
# IP vs Load Balancer
An origin server can be hosted with just a public IP on the Internet, or behind a load balancer (aka LB).
There's different ways to set a LB. The simplest version is to have an origin DNS configuration with two A records pointing to two public IPs. For example:
lb.tenant.com. 300 IN A 120.120.120.1
lb.tenant.com. 300 IN A 120.120.120.2
This is called round-robin, and it means that each time a DNS from a user needs to resolve lb.tenant.com, it will get one of those IPs randomly, in this case, for 300 seconds (5 minutes).
On the next resolve, it will get a new random value.
This way requests are "balanced" to the two IPs randomly.
TIP
MarfeelCDN works whether the origin uses an IP directly or a Load Balancer.
# Point of Presence
Point of Presence (POP) are cache servers distributed around the world. Their purpose is to serve cached content from the geographically closest location to reduce latency.
TIP
Fastly's POPs are named after the closest airport codes. These codes can be found in the x-served-by cache header. e.g. A request with x-served-by: cache-mad22045-MAD was served from a POP near Madrid.
Within Marfeel, Fastly's CDN POP Network (opens new window) is used to distribute the content.
# Request, Response & Status codes
A request is the action of trying to access an address that belongs to a server. For HTTP requests, find here (opens new window) the methods allowed.
A response is what the server the address was requested from, answers. This response will always contain a status code with information about the response itself.
Find all HTTP standard status codes here. (opens new window)
# Service Workers
A service worker is a type of web worker. It's essentially a JavaScript file that runs separately from the main browser thread, intercepting network requests, caching or retrieving resources from the cache, and delivering push messages.
Service Workers improve the performance of Marfeel by caching several resources, reducing the network load. They also allow serving content when there's no internet connection by using cached data.
Service Workers enable the activation of PWA experience.
Learn all about Service Workers in the developers.google article (opens new window).
# SSL
SSL is a security protocol that provides privacy, authentication, and integrity to Internet communications. SSL eventually evolved into Transport Layer Security (TLS).
Transport Layer Security, or TLS, is a widely adopted security protocol designed to facilitate privacy and data security for communications over the Internet. A primary use case of TLS is encrypting the communication between web applications and servers, such as web browsers loading a website.
For in depth reading on SSL & TSL check this article (opens new window).
# TTL
Time to live (TTL) has different meanings deppending on what we apply it to.
# TTL(Cache)
When talking about Cache, time to live (TTL) is the time that an object is stored in a caching system before it’s deleted or refreshed.
TIP
Check the cache headers article for details on how it's used in Marfeel.
# TTL(DNS)
In DNS context, TTL is the time a response from the DNS server is considered valid.
TIP
This value can be seen when executing the dig command on a resource from the command line.
$ dig example.com
example.com. 300 IN A 121.131.132.117
In the answer section, the 300 says this response is cached for 5 minutes (=300s) by the DNS server. This means that even if changes are applied to the DNS configuration, they are not visible for the next 5 minutes.
# TXT Record
TXT records are a type of Domain Name System (DNS) record that contains text information for sources outside of your domain.
Marfeel uses a TXT record to verify domain ownership (opens new window). Fastly's certification partner authority, GlobalSign, handles it.
TIP
TXT Record must be added by the tenant before MarfeelCDN activation.