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Cloudflare Fundamentals

What is Cloudflare?
1 min read

Cloudflare is a global network of servers

. When you add your application to Cloudflare, we use this network to sit in between
requests and your origin server.

This position allows us to do several things — speeding up content delivery and user
experience ( CDN), protecting your website from malicious activity ( DDoS, Web Application
Firewall), routing traffic (Load balancing, Waiting Room), and more.

How Cloudflare works
3 min read

Fundamentally, Cloudflare is a large network of servers that can improve the security,
performance, and reliability of anything connected to the Internet.

Cloudflare does this by serving as a reverse proxy

for your web traffic. All requests to and from your origin flow through Cloudflare and — as
these requests pass through our network — we can apply various rules and optimizations to
improve security, performance, and reliability.

Life of a request
Even though it feels pretty instantaneous, there’s a lot happening when you type
www.example.com into your browser.

A website’s content does not technically live at a URL like www.example.com, but rather at
an IP address like 192.0.2.1. It’s similar to how we say that Cloudflare’s headquarters is
101 Townsend St., San Francisco, CA 94107, but really that address is just a placeholder for
latitude and longitude coordinates (37.780259, -122.390519). URLs and street addresses
are much easier for humans to remember.

The process of converting a human-readable URL (www.example.com) into a
machine-friendly address (192.0.2.1) is known as a DNS lookup
.

Without Cloudflare

Without Cloudflare, DNS lookups for your application’s URL return the IP address of your
origin server

URL Returned IP
address

example.c 192.0.2.1
om

When using Cloudflare with unproxied DNS records, DNS lookups for unproxied domains or
subdomains also return your origin’s IP address.

Another way of thinking about this concept is that visitors directly connect with your origin
server.

ConnectionVisitor
Origin server

With Cloudflare

With Cloudflare — meaning your domain or subdomain is using proxied DNS records —
DNS lookups for your application’s URL will resolve to Cloudflare Anycast IPs

instead of their original DNS target.

URL Returned IP
address

example.c 104.16.77.250
om

This means that all requests intended for proxied hostnames will go to Cloudflare first and
then be forwarded to your origin server.

Visitor ← Connection → Cloudflare global network ←Connection→Origin Server

Cloudflare assigns specific Anycast IPs to your domain dynamically and these IPs may
change at any time. This is an expected part of the operation of our Anycast network and
does not affect the proxy behavior described above.

Benefits
When your traffic is proxied through Cloudflare before reaching your origin server, your
application gets additional security, performance, and reliability benefits.

Security

Beyond hiding your origin’s IP address from potential attackers, Cloudflare also stops
malicious traffic before it reaches your origin web server.

Cloudflare automatically mitigates security risks using our WAF and DDoS protection.

For additional details on security, refer to our guide on how to Secure your website.

Performance

For proxied traffic, Cloudflare also serves as a Content Delivery Network (CDN)

, caching static resources and otherwise optimizing asset delivery.

For additional details on performance, refer to our guides on Optimizing Site Speed and
Caching.

Reliability

Cloudflare’s globally distributed Anycast network

routes visitor requests to the nearest Cloudflare data center.

Combined together with our CDN

and DDoS protection, our network helps keep your application online.

Cloudflare IPs
2 min read

Cloudflare has several IP address ranges

which are shared by all proxied hostnames.

Together, these IP addresses form the backbone of our Anycast network

, helping distribute traffic amongst various edge network servers.

Cloudflare uses other IP ranges for various products and services, but these addresses will
not make connections to your origin.

Allow Cloudflare IP addresses
Because of how Cloudflare works, all traffic to proxied DNS records pass through Cloudflare
before reaching your origin server. This means that your origin server will stop receiving
traffic from individual visitor IP addresses and instead receive traffic from Cloudflare IP
addresses

, which are shared by all proxied hostnames.

This setup can cause issues if your origin server blocks or rate limits connections from
Cloudflare IP addresses. Because all visitor traffic will appear to come from Cloudflare IP
addresses, blocking these IPs — even accidentally — will prevent visitor traffic from
reaching your application.

To avoid rate limiting or blocking these requests, you will need to allow Cloudflare IPs at your
origin server.

For Magic Transit customers, Cloudflare routes the traffic instead of proxying it. Once
Cloudflare starts advertising your IP prefixes, it will accept IP packets destined for your
network, process them, and then output these packets to your origin infrastructure.

Customize Cloudflare IP addresses
If they do not want to use Cloudflare IP addresses — which are shared by all proxied
hostnames — Enterprise customers have two potential alternatives:

● Bring Your Own IP (BYOIP): Cloudflare announces your IPs in all our locations.
● Static IP addresses: Cloudflare sets static IP addresses for your domain. For more
details, contact your account team.

Business and Enterprise customers can also reduce the number of Cloudflare IPs that their
domain shares with other Cloudflare customer domains by uploading a Custom SSL
certificate.

Reference architectures
1 min read

Reference architecture documents and diagrams are designed to provide a foundational
knowledge of Cloudflare solutioning for a variety of products. Building on the information in
these documents, you can architect software solutions based on your specific context and
needs.

● Content Delivery Network
● Magic Transit
● Multi-vender Application Security and Performance
Account setup
To create a Cloudflare account:

1. Go to the Sign up page
1. .
2. Enter your Email and Password.
3. Click Create Account.

Once you create your account, Cloudflare will automatically send an email to your address to
verify that email address.

Best practices
If you are creating an account for your team or a business, we recommend choosing an
email alias or distribution list for your Email, such as [email protected].

This email address is the main point of contact for your Cloudflare billing, usage notifications,
and account recovery.

Set-up 2FA
2 min read

Two-factor authentication (2FA) allows user account owners to add an additional layer of
login security to Cloudflare accounts. This additional authentication step requires you to
provide both something you know, such as a Cloudflare password, and something you have,
such as an authentication code from a mobile device.

Cloudflare user accounts configured to use single sign-on (SSO) cannot configure 2FA.

Cloudflare offers the option to use either a phishing-resistant security key, like a YubiKey, or
a Time-Based One-Time password (TOTP) mobile app for authentication, like Google
Authenticator, or both. If you add both of these authentication methods to your account, you
are initially prompted to log in with the security key, but can opt-out and use TOTP instead.

To ensure that you can securely access your account even without your mobile device or
security keys, Cloudflare also provides backup codes for download.

Tip

After downloading your backup codes, we recommend saving them in a secure location.

As the user account owner, you are automatically assigned the Super Administrator role.
Once 2FA is enabled, all Cloudflare account members are required to configure 2FA on their
mobile devices.
Enable 2FA
We recommend that all Cloudflare user account holders enable two-factor authentication
(2FA) to keep your accounts secure.

2FA can only be enabled successfully on an account with a verified email address. If you do
not verify your email address first, you may lock yourself out of your account.

Super Administrators can turn on 2FA Enforcement to require all members to enable 2FA. If
you are not a Super Administrator, you will be forced to turn on 2FA prior to accepting the
invitation to join a Cloudflare account as a member.

To enable two-factor authentication for your Cloudflare login:

1. Log in to the Cloudflare dashboard
1. .
2. Under the My Profile dropdown, select My Profile.
3. Select Authentication.
4. Select Manage in the Two-Factor Authentication card.
5. Configure either a TOTP mobile app or a security key to enable 2FA on your account.

Additional configurations
Cloudflare also supports 2FA with device built-in authenticators (Apple Touch ID, Android
fingerprint, or Windows Hello), Yubikeys and TOTP mobile applications.

Customize your account
2 min read

After creating an account, here are a handful of configurations you can customize:

Account name
Your account name defaults to <<YOUR_EMAIL_ADDRESS>>'s Account.

You may want to customize the name of this account, either to help specify its purpose or to
help associated with multiple accounts.

To change your account name:

1. Log into the Cloudflare dashboard
1. .
2. Go to Manage Account > Configurations.
3. For Account Name, select Change Name.
4. Enter a new account name.
5. Select Save.

Appearance
If you want to adjust how the Cloudflare dashboard appears on your device, you can adjust
relevant settings in your account Profile.

To update appearance preferences:

1. Log into the Cloudflare dashboard
1. .
2. Go to My Profile
3. For Appearance, choose a value:
○ Dark: Defaults to darker colors.
○ Light: Defaults to lighter colors.
○ Use system setting: Defaults to whatever is used on your device.
4. Your dashboard display will update to the new appearance setting automatically.

Communication preferences
When you create an account, Cloudflare automatically chooses your Communication
Preferences, or when Cloudflare might occasionally send you emails.

To update the communication preferences for your profile (which requires a verified email
address):

1. Log into the Cloudflare dashboard
1. .
2. Go to My Profile
3. For Communication Preferences, select Edit.
4. If you want a specific category of emails, make sure its associated box is checked.
5. Select Save.

Language preferences
After you create your account, you may want to update your language preference.

To update the language preference for your profile:

1. Log into the Cloudflare dashboard

Go to My Profile
For Language Preference, select a value.

Your dashboard display will update to the new language automatically.

Add and manage other members
3 min read

Learn how to add new account members, edit or revoke their permissions and access, and
resend verifications emails.

To manage account members, you must have a role of Super Administrator and have a
verified email address.

View account members
To manage account members, you must have a role of Super Administrator and have a
verified email address.

Dashboard mode:

To view members using the dashboard:

1. Log in to the Cloudflare dashboard

and select your account.

Go to Manage Account > Members.

API mode:

To view members using the API, send a GET request.

Baseurl:

GET https://api.cloudflare.com/client/v4

An API key is a token that you provide when making API calls. Include the token in a header parameter called
X-Auth-Email.

Example: X-Auth-Email: 123

An API key is a token that you provide when making API calls. Include the token in a header parameter called
X-Auth-Key.

Example: X-Auth-Key: 123

An API key is a token that you provide when making API calls. Include the token in a header parameter called
X-Auth-User-Service-Key.

Example: X-Auth-User-Service-Key: 123
Provide your bearer token in the Authorization header when making requests to protected resources.

Example: Authorization: Bearer 123

Interact with Cloudflare's products and services via the Cloudflare API.

Using the Cloudflare API requires authentication so that Cloudflare knows who is making
requests and what permissions you have. Create an API token to grant access to the API to
perform actions.

To create an API token, from the Cloudflare dashboard, go to My Profile > API Tokens and
select Create Token.

Add account members
To manage account members, you must have a role of Super Administrator and have a
verified email address.

Dashboard mode:

To add a member to your account:

1. Log in to the Cloudflare dashboard
1. and select your account.
2. Go to Manage Account > Members.
3. Select Invite.
4. Fill out the following information:
○ Invite members: Enter one or more email addresses (if multiple, separate
addresses with commas).
○ Scope: Use a variety of fields to adjust the scope of your roles.
○ Roles: Choose one or more roles to assign your members.
5. Select Continue to summary.
6. Review the information, then select Invite.

If a user already has an account with Cloudflare and you have an Enterprise account, you
can also select Direct Add to add them to your account without sending an email invitation.

API mode:

POST https://api.cloudflare.com/client/v4/accounts/{account_identifier}/members

Request Sample

curl --request POST \

--url https://api.cloudflare.com/client/v4/accounts/account_identifier/members \

--header 'Content-Type: application/json' \

--header 'X-Auth-Email: ' \
--data '{

"email": "[email protected]",

"roles": [

"3536bcfad5faccb999b47003c79917fb"

"status": "pending"

Response Example

{

"errors": [],

"messages": [],

"result": {

"id": "4536bcfad5faccb111b47003c79917fa",

"roles": [

{

"description": "Administrative access to the entire Account",

"id": "3536bcfad5faccb999b47003c79917fb",

"name": "Account Administrator",

"permissions": {

"analytics": {

"read": true,

"write": false

"zones": {

"read": true,

"write": true
}

}

"status": null,

"user": {

"email": "[email protected]",

"first_name": "John",

"id": "023e105f4ecef8ad9ca31a8372d0c353",

"last_name": "Appleseed",

"two_factor_authentication_enabled": false

"code": "05dd05cce12bbed97c0d87cd78e89bc2fd41a6cee72f27f6fc84af2e45c0fac0"

"success": true

}

Resend an invitation
If you invited a member to your account but they cannot find the invitation or the invitation
expires, you can resend the invitation through the Cloudflare dashboard:

1. Log in to the Cloudflare dashboard and select your account[^1].

2. Go to Manage Account > Members.

3. Select a member record where their Status is Invite Pending.

4. Select Resend invite

Create an API token
2 min read
Prerequisite

Before you begin, find your zone and account IDs.

1. From the Cloudflare dashboard, go to My Profile > API Tokens.
2. Select Create Token.
3. Select a template from the available API token templates or create a custom token.
We use the Edit zone DNS template in the following examples.
4. Add or edit the token name to describe why or how the token is used. Templates are
prefilled with a token name and permissions.
5. Modify the token’s permissions. After selecting a permissions group (Account, User,
or Zone), choose what level of access to grant the token. Most groups offer Edit or
Read options. Edit is full CRUDL (create, read, update, delete, list) access, while
Read is the read permission and list where appropriate. Refer to the available token
permissions for more information.
6. Select which resources the token is authorized to access. For example, granting
Zone DNS Read access to a zone example.com will allow the token to read DNS
records only for that specific zone. Any other zone will return an error for DNS record
reads operations. Any other operation on that zone will also return an error.
7. (Optional) Restrict how a token is used in the Client IP Address Filtering and TTL
(time to live) fields.
8. Select Continue to summary.
9. Review the token summary. Select Edit token to make adjustments. You can also
edit a token after creation.
10. Select Create Token to generate the token’s secret.
11. Copy the secret to a secure place.

Warning

The token secret is only shown once. Do not store the secret in plaintext where others can
access it. Anyone with this token can perform the authorized actions against the resources
that the token has access to.

The token secret page also includes an example command to test the token. Use the
/user/tokens/verify endpoint to fetch the current status of the given token.

$ curl "https://api.cloudflare.com/client/v4/user/tokens/verify" \
-H "Authorization: Bearer <API_TOKEN>"

The result:

{
"result": {
"id": "100bf38cc8393103870917dd535e0628",
"status": "active"
},
"success": true,
"errors": [],
"messages": [
{
"code": 10000,
"message": "This API Token is valid and active",
"type": null
}
]

}

With this you have successfully created an API token and can start working with the
Cloudflare API. After creating your first API token, you can create additional API tokens via
the API.

Add your domain to Cloudflare

Minimize downtime

2 min read

When making any change to the routing of an Internet application, there is always a
possibility of downtime due to certificate issuance, misconfigured settings, or limitations at
your origin server. To avoid downtime when going live, it’s important to review the most
common configurations.

Update and review DNS records.
Before activating your domain on Cloudflare (exact steps depend on your DNS setup),
review the DNS records in your Cloudflare account.

Start with unproxied records

With a new domain, make sure all your DNS records have a proxy status of DNS-only.

This setting prevents Cloudflare from proxying your traffic before you have an active edge
certificate or before you have allowed Cloudflare IP addresses.
Confirm record accuracy

Take extra time to confirm the accuracy of your DNS records before activating your domain,
paying special attention to:

● Zone apex records (example.com)
● Subdomain records (www.example.com or blog.example.com)
● Email records

If you add DNS records to your authoritative DNS provider between onboarding your domain
and activating your domain, you may need to also add these records within Cloudflare.

Activate your domain.
Finish the DNS setup for your domain, moving the domain status to Active:

● Full setups: Update the authoritative nameservers at your registrar and wait for that
change to be authenticated.
● Partial setups: Add the verification TXT record to your authoritative DNS and wait for
that change to be authenticated.

Verify SSL/TLS edge certificates.
Before proxying your traffic through Cloudflare, verify that Cloudflare has an active Edge
Certificate for your domain.

For more details about timing and certificate recommendations, refer to Certificate issuance.

Optional - Test configuration.
You may want to test your configuration using your local machine or proxying traffic from a
development domain or subdomain.

If you experience issues, you should make sure that you have allowed Cloudflare IP
addresses at your origin server.

Update proxy status.
Once you have verified that your SSL/TLS edge certificate is active and you have allowed
Cloudflare IP addresses, change the proxy status of appropriate DNS records to Proxied.

Allow Cloudflare IP addresses
2 min read
Because of how Cloudflare works, all traffic to proxied DNS records pass through Cloudflare
before reaching your origin server. This means that your origin server will stop receiving
traffic from individual visitor IP addresses and instead receive traffic from Cloudflare IP
addresses

, which are shared by all proxied hostnames.

To avoid rate limiting or blocking these requests, you will need to allow Cloudflare IPs at your
origin server.

Review external tools
To avoid blocking Cloudflare IP addresses unintentionally, review your external tools to
check that:

● Any security plugins — such as those for WordPress — allow Cloudflare IP
addresses.
● The mod_security
● plugin is up to date.

Configure origin server
Allowlist Cloudflare IP addresses

To avoid blocking Cloudflare IP addresses unintentionally, you also want to allow Cloudflare
IP addresses at your origin web server.

You can explicitly allow these IP addresses with a .htaccess file or by using iptables.

The following example demonstrates how your could use an iptables rule to allow a
Cloudflare IP address range. Replace $ip below with one of the Cloudflare IP address
ranges

# For IPv4 addresses
iptables -I INPUT -p tcp -m multiport --dports http,https -s $ip -j ACCEPT
# For IPv6 addresses
ip6tables -I INPUT -p tcp -m multiport --dports http,https -s $ip -j ACCEPT
Block other IP addresses (recommended)

As a best practice, we also recommend that you explicitly block all traffic that does not come
from Cloudflare IP addresses or the IP addresses of your trusted partners, vendors, or
applications.

For example, you might update your iptables

with the following commands:
#for IPv4
iptables -A INPUT -p tcp -m multiport --dports http,https -j DROP
#for IPv6
ip6tables -A INPUT -p tcp -m multiport --dports http,https -j DROP

Disable DNSSEC
2 min read

DNS Security Extensions (DNSSEC) adds an extra layer of authentication to DNS, ensuring
requests are not routed to a spoofed domain.

Disable DNSSEC
If you are onboarding an existing domain to Cloudflare, make sure DNSSEC is disabled at
your registrar (where you purchased your domain name). Otherwise, your domain will
experience connectivity errors when you change your nameservers.

Why do I have to disable DNSSEC?

When your domain has DNSSEC enabled, your DNS provider digitally signs all your DNS
records. This action prevents anyone else from issuing false DNS records on your behalf
and redirecting traffic intended for your domain.

However, having a single set of signed records also prevents Cloudflare from issuing new
DNS records on your behalf (which is part of using Cloudflare for your authoritative
nameservers). So if you change your nameservers without disabling DNSSEC, DNSSEC will
prevent Cloudflare’s DNS records from resolving properly.

Add a site
2 min read

1. Log in to the Cloudflare dashboard.
2. In the top navigation bar, click Add site.
3. Enter your website’s apex domain (example.com) and then click Add Site.

If Cloudflare is unable to identify your domain as a registered domain, make sure you are
using an existing top-level domain

(.com, .net, .biz, or others).

Additionally, Cloudflare requires your apex domain to be one level below a valid TLD
defined in the Public Suffix List (PSL).

1. Select your plan level. For more details on features and pricing, refer to our Plans
page
.
2. Review your DNS records.
When you add a new site to Cloudflare, Cloudflare automatically scans for common
records and adds them to the DNS zone. The records show up under the respective
zone DNS > Records page.

3. Since this scan is not guaranteed to find all existing DNS records, you need to review
your records, paying special attention to the following record types:
a. Zone apex records (example.com)
b. Subdomain records (www.example.com or blog.example.com)
c. Email records
4. If you activate your domain on Cloudflare without setting up the correct DNS records
for your domain and subdomain, your visitors may experience
DNS_PROBE_FINISHED_NXDOMAIN errors.
5. If you find any missing records, manually add those records.
6. Depending on your site setup, you may want to adjust the proxy status for certain A,
AAAA, or CNAME records.
7. Click Continue.
8. Go through the Quick Start Guide and when you have finished, click Finish.

Update your nameservers
1 min read

Once you have added a domain (also known as a zone) to Cloudflare, that domain will
receive two assigned authoritative nameservers.

Before your domain can begin using Cloudflare for DNS resolution, you need to add these
nameservers at your registrar. Make sure DNSSEC is disabled at this point.

Domain Resolution
Ensure all your traffic is proxying through Cloudflare successfully.

Objectives
By the end of this module, you will be able to:

● Confirm your zone is set up correctly on Cloudflare
● Recognize and troubleshoot issues with your DNS records and SSL/TLS certificates

Review DNS records
1 min read

When you add a new site to Cloudflare, Cloudflare automatically scans for common records
and adds them to the DNS zone. The records show up under the respective zone DNS >
Records page.

The DNS records quick scan is not automatically invoked in the following cases:

● If you choose Enterprise plan and, instead of the Quick Scan, choose to upload a
DNS zone file or add records manually.
● If you add a zone via the API.

You can manually invoke the quick scan via API with the Scan DNS Records endpoint. Note
that the quick scan is a best effort attempt based on a predefined list of commonly used
record names and types. You can read more about this in the reference page.

Since this scan is not guaranteed to find all existing DNS records, you need to review your
records, paying special attention to the following record types:

● Zone apex records (example.com)
● Subdomain records (www.example.com or blog.example.com)
● Email records

If you want more control over which DNS records are imported and how, import a zone file.

If your domain is added to Cloudflare by a hosting partner, manage your DNS records via the
hosting partner.

Proxy status
3 min read

The Proxy status of a DNS record affects how Cloudflare treats incoming traffic to that
record. Cloudflare recommends enabling our proxy for all A, AAAA, and CNAME records.
Proxied records
Note that if you have multiple A/AAAA records on the same name and at least one of them is
proxied, Cloudflare will treat all A/AAAA records on this name as being proxied.

When you proxy specific DNS records through Cloudflare - specifically A, AAAA, or CNAME
records — DNS queries for these will resolve to Cloudflare Anycast IPs instead of their
original DNS target. This means that all requests intended for proxied hostnames will go to
Cloudflare first and then be forwarded to your origin server.

This behavior allows Cloudflare to optimize, cache, and protect all requests to your
application, as well as protect your origin server from DDoS attacks

Because requests to proxied hostnames go through Cloudflare before reaching your origin
server, all requests will appear to be coming from Cloudflare’s IP addresses (and could
potentially be blocked or rate limited). If you use proxied records, you may need to adjust
your server configuration to allow Cloudflare IPs.

Cloudflare Anycast IPs used to proxy traffic on your domain are assigned automatically.
These IPs might change at any time for operational reasons. If you need to allowlist
Cloudflare IPs on your infrastructure or hosting provider, include the full list of Cloudflare
Anycast IPs

As an Enterprise customer, you have the option to get static IPs or bring your own IPs
(BYOIP).

Limitations
Record types

By default, Cloudflare only supports proxied A, AAAA, and CNAME records. You cannot proxy
other record types.

If you encounter a CNAME record that you cannot proxy — usually associated with another
CDN provider — a proxied version of that record will cause connectivity errors. Cloudflare is
purposely preventing that record from being proxied to protect you from a misconfiguration.

Ports and protocols

By default, Cloudflare only proxies HTTP and HTTPS traffic.

If you need to connect to your origin using a non-HTTP protocol (SSH, FTP, SMTP) or the
traffic targets an unsupported port at the origin, either leave your records unproxied
(DNS-only) or use Cloudflare Spectrum.

Pending domains

When you add a domain to Cloudflare, Cloudflare protection will be in a pending state until
we can verify ownership. This could take up to 24 hours to complete.
This means that DNS records - even those set to proxy traffic through Cloudflare – will be
DNS-only until your zone has been activated and any requests to your DNS records will
return your origin server’s IP address.

If this warning is still present after 24 hours, refer to Troubleshooting.

For enhanced security, we recommend rolling your origin IP addresses at your hosting
provider after your zone has been activated. This action prevents your origin IPs from being
leaked during onboarding.

Windows authentication

Because Microsoft Integrated Windows Authentication, NTLM, and Kerberos violate
HTTP/1.1 specifications, they are not compatible with proxied DNS records.

Enable DNSSEC
2 min read

DNS Security Extensions (DNSSEC) adds an extra layer of authentication to DNS, ensuring
requests are not routed to a spoofed domain.

For additional background on DNSSEC, visit the Cloudflare Learning Center

When you enable DNSSEC, Cloudflare signs your zone, publishes your public signing keys,
and generates your DS record.

Step 1 - Activate DNSSEC in Cloudflare
1. Log in to the Cloudflare dashboard
1. and select your account and domain.
2. Go to DNS > Settings.
3. For DNSSEC, click Enable DNSSEC.
4. In the dialog, you have access to several necessary values to help you create a DS
record at your registrar. Once you close the dialog, you can access this information
by clicking DS record on the DNSSEC card.

Step 2 — Add DS record to your registrar
Add the DS record to your registrar. If Algorithm 13 - Cloudflare’s preferred cipher choice - is
not listed by your registrar, it may also be called ECDSA Curve P-256 with SHA-256.

Provider-specific instructions
Note:
Cloudflare automatically adds DS records for domains using Cloudflare Registrar or those
using .ch and .cz top-level domains.

Create a subdomain
1 min read

Most subdomains serve a specific purpose within the overall context of your website. For
example, blog.example.com might be your blog, support.example.com could be your
customer help portal, and store.example.com would be your e-commerce site.

Subdomain records
To create a new subdomain, you would first add the subdomain content at your host.

Then, you would create a corresponding A, AAAA, or CNAME record for that subdomain
(blog, store).

Type Name IPv4 Proxy
address status

A www 192.0.2.1 Proxied

Set up email records
1 min read

Receive email
If you only need to receive emails, Cloudflare offers Email Routing for free email forwarding
to custom email addresses.

Send and receive email
To send and receive emails from your domain, you need:

● An SMTP provider.
● To create two DNS records within Cloudflare.

To route emails through Cloudflare and to your mail server:
1. Get the IP address and MX record details from your SMTP provider (vendor-specific
guidelines).
2. Add an A or AAAA record for your mail subdomain that points to the IP address of
your mail server.
Type Name IPv4 Proxy
address status

A mail 192.0.2.1 DNS only

3. API example
4. Add an MX record that points to that subdomain.
Type Name Mail server TTL

MX @ mail.example. Auto
com
API Example:

Request:
curl -sX POST "https://api.cloudflare.com/client/v4/zones/<ZONE_ID>/dns_records" \

-H 'x-auth-email: <EMAIL>' \

-H 'x-auth-key: <API_KEY>' \

-H "Content-Type: application/json" \

--data '{
"type":"MX",
"name":"example.com",
"content":"mail.example.com",
"ttl":3600
}'
Response:
{
"result": {
"id": "<ID>",
"zone_id": "<ZONE_ID>",
"zone_name": "example.com",
"name": "example.com",
"type": "MX",
"content": "mail.example.com",
"priority": 10,
"proxiable": false,
"proxied": false,
"ttl": 3600,
"locked": false,
"meta": {
"auto_added": false,
"managed_by_apps": false,
"managed_by_argo_tunnel": false,
"source": "primary"
},
"comment": null,
"tags": [],
"created_on": "2023-01-17T20:54:23.660869Z",
"modified_on": "2023-01-17T20:54:23.660869Z"
},
"success": true,
"errors": [],
"messages": []

}

Default improvements
1 min read

When your DNS records are proxied through Cloudflare, Cloudflare provides free and
unmetered DDoS protection and other protection measures through the Web Application
Firewall (WAF).

DDoS protection
A distributed denial-of-service (DDoS) attack is where a large number of computers or
devices, usually controlled by a single attacker, attempt to access a website or online service
all at once. This flood of traffic can overwhelm the website’s origin servers, causing the site
to slow down or even crash.

For more information about DDoS attacks and Cloudflare DDoS protection, refer to Prevent
DDoS attacks.

Managed rulesets
All customers have access to the Cloudflare Free Managed Ruleset, which provides
mitigations against high and wide-impacting vulnerabilities.

For more details, refer to the WAF documentation.

SSL/TLS settings
2 min read

Once you make sure that your Cloudflare SSL/TLS is working correctly, you will likely want
to customize your SSL/TLS setup.

Encryption mode
Your zone’s SSL/TLS Encryption Mode controls how Cloudflare manages two connections:
one between your visitors and Cloudflare, and the other between Cloudflare and your origin
server.

Basic setup

The simplest way to choose your encryption mode is to enable the SSL/TLS
Recommender, which scans your domain and recommends the appropriate setting.

To make sure you do not inadvertently block the SSL/TLS Recommender, review your
settings to make sure your domain:

● Is accessible.
● Is not blocking requests from our bot (which uses a user agent of
Cloudflare-SSLDetector).
● Does not have any active, SSL-specific Page Rules or Configuration rules.

Then, you can enable SSL/TLS recommendations in the dashboard:

1. Log in to the Cloudflare dashboard
1. and select your account and application.
2. Go to SSL/TLS.
3. For SSL/TLS Recommender, switch the toggle to On.

Once enabled, the SSL/TLS Recommender runs an origin scan using the user agent
Cloudflare-SSLDetector and ignores your robots.txt file (except for rules explicitly
targeting the user agent).

Based on this initial scan, the Recommender may decide that you could use a stronger SSL
encryption mode. It will never recommend a weaker option than what is currently configured.

If so, it will send the application owner an email with the recommended option and add a
Recommended by Cloudflare tag to that option on the SSL/TLS page. You are not required
to use this recommendation.

If you do not receive an email, keep your current SSL encryption mode.

Secure setup
If possible, Cloudflare recommends using Full or Full (strict) modes to prevent malicious
connections to your origin.

These modes usually require additional setup and can be more technically challenging.

Enforce HTTPS connections
Even if your application has an active edge certificate, visitors can still access resources
over unsecured HTTP connections.

Using various Cloudflare settings, however, you can force all or most visitor connections to
use HTTPS.

Evaluate additional features
After you have chosen your encryption mode and enforced HTTPS connections, evaluate
the following settings:

● Edge certificates: Customize different aspects of your edge certificates, from enabling
Opportunistic Encryption to specifying a Minimum TLS Version.
● Authenticated origin pull: Ensure all requests to your origin server originate from the
Cloudflare network.
● Notifications: Set up alerts related to certificate validation status, issuance,
deployment, renewal, and expiration.

Bot Fight Mode
1 min read

Bot Fight Mode is a simple, free product that helps detect and mitigate bot traffic on your
domain. When enabled, the product:

● Identifies traffic matching patterns of known bots
● Issues computationally expensive challenges in response to these bots
● Notifies Bandwidth Alliance
● partners (if applicable) to disable bots

Considerations
Bot Fight Mode has a few limitations, including that it:

● Protects entire domains without endpoint restrictions.
● Cannot be customized, adjusted, or reconfigured via WAF custom rules.

If these limitations could cause issues with your application, do not enable this feature.

For more granular control - including the ability to use the Skip action for bot mitigation -
consider using Super Bot Fight Mode.

Setup
To start using Bot Fight Mode:

1. Log in to the Cloudflare dashboard

and select your account and domain.
Go to Security > Bots.
For Bot Fight Mode, select On.

Secure your origin
4 min read

Your origin server

is a physical or virtual machine that is not owned by Cloudflare and hosts your application
content (data, webpages, etc.).

Receiving too many requests can be bad for your origin. These requests might increase
latency for visitors, incur higher costs — particularly for cloud-based machines — and could
knock your application offline.

Secure origin connections
When you secure origin connections, it prevents attackers from discovering and overloading
your origin server with requests.

● DNS:
1. Proxy records (when possible): Set up proxied (orange-clouded) DNS
records to hide your origin IP addresses and provide DDoS protection. As
part of this, you should allow Cloudflare IP addresses at your origin to prevent
requests from being blocked.
2. Review DNS-only records: Audit existing DNS-only records (SPF, TXT, and
more) to make sure they do not contain origin IP information.
3. Evaluate mail infrastructure: If possible, do not host a mail service on the
same server as the web resource you want to protect, since emails sent to
non-existent addresses get bounced back to the attacker and reveal the mail
server IP.
4. Rotate origin IPs: Once onboarded, rotate your origin IPs, as DNS records
are in the public domain. Historical records are kept and would contain IP
addresses prior to joining Cloudflare

Application layer

1. Cloudflare Tunnel (HTTP/WebSockets)

Cloudflare Tunnel connects your resources to Cloudflare without a publicly routable IP
address, by creating an outbound-only connections to Cloudflare’s global network.

● Security: Very secure.
● Availability: All customers.
● Challenges: Requires installing the cloudflared daemon on origin server or
virtual machine.

2. HTTP Header Validation

Only allow traffic with specific (and secret) HTTP headers.

● Security: Moderately secure.
● Availability: All customers.
● Challenges:
1. Requires more configuration efforts on application- and server-side to accept
those headers.
2. Basic authentication is vulnerable to replay attacks. Because basic
authentication does not encrypt user credentials, it is important that traffic
always be sent over an encrypted SSL session.
3. There might be valid use cases for a mismatch in SNI / Host headers such as
through Page Rules, Load Balancing, or Workers, which all offer HTTP Host
Header overrides.
● Process:
1. Use Transform rules or Workers to add an HTTP Auth Header.
2. Configure your origin server to restrict access based on the HTTP Auth
Header (or perform HTTP Basic Authentication).
3. Configure your origin server to restrict access based on the HTTP Host
Header. Specifically, only allow requests which contain expected HTTP Host
Header values, and reject all other requests.

3. JSON Web Tokens (JWT) Validation

Only allow traffic with the appropriate JWT.

● Security: Very secure.
● Availability: Some customers.
● Challenges:
○ Requires either installing incremental software or modifying application code.
○ Lots of manual work.
● Resources:
○ Validate JWTs for an Access application
○ Validate JWTs for an API

Transport Layer

Authenticated Origin Pulls

Authenticated Origin Pulls helps ensure requests to your origin server come from the
Cloudflare network.

● Security: Very secure.
● Availability: All customers.
● Challenges:
○ Requires Full or Full (strict) encryption modes.
○ Requires more configuration efforts for application and server, such as
uploading a certificate and configuring the server to use it.
○ For more strict security, you should upload your own certificate. Although
Cloudflare provides you a certificate for easy configuration, this certificate
only guarantees that a request is coming from the Cloudflare network.
○ Not scalable for large numbers of origin servers.

Cloudflare Tunnel (SSH / RDP)

Cloudflare Tunnel connects your resources to Cloudflare without a publicly routable IP
address, by creating an outbound-only connections to Cloudflare’s global network.

● Security: Very secure.
● Availability: All customers.
● Challenges: Requires installing the cloudflared daemon on origin server or
virtual machine.

Network Layer

Allowlist Cloudflare IP addresses

Explicitly block all traffic that does not come from Cloudflare IP addresses (or the IP
addresses of your trusted partners, vendors, or applications).

● Security: Moderately secure.
● Availability: All customers.
● Challenges:
○ Requires allowlisting Cloudflare IP ranges at your origin server.
○ Vulnerable to IP spoofing.
Cloudflare Network Interconnect

Cloudflare Network Interconnect allows you to connect your network infrastructure directly
with Cloudflare – rather than using the public Internet – for a more reliable and secure
experience.

● Security: Very secure.
● Availability: Enterprise-only.
● Challenges
○ Requires some networking knowledge.
○ Only applies to some customer use cases.

Cloudflare Aegis

prevents external connections by providing dedicated egress IP addresses.

● Security: Very secure.
● Availability: Enterprise-only.
● Challenges: Requires network-level firewall policies.

Security Center
1 min read

Cloudflare Security Center brings together our suite of security products, our security
expertise, and unique Internet intelligence as a unified security intelligence solution. Security
Center enables you to strengthen your security posture by:

● Mapping your cyber attack surface
● Providing asset inventory and discovery
● Identifying potential security risks, misconfigurations, and vulnerabilities
● Helping you to mitigate these risks through remediation in a few clicks

For additional details and help, refer to the Security Center documentation.

Setup
To enable Security Insights and perform an initial security scan:

1. Log in to the Cloudflare dashboard
1. and select your account.
2. In the Account Home, go to Security Center > Security Insights.
3. Under Enable Security Center scans, select Start scan.
The initial Security Insights scan will start. The initial scan time depends on the number of IT
assets in all the domains of your Cloudflare account. When the scan is complete, the status
of the page will change from Scan in Progress to Last scan performed on:
<DATE_TIME>.

Performance
Improve your application’s performance by enabling and optimizing your sites settings.

Objectives
By the end of this module, you will be able to:

● Explain how - just by using Cloudflare - you can increase application performance
● Optimize caching using various Cloudflare settings
● Improve performance using different settings within Speed settings
● Set up Cloudflare Web Analytics for free, privacy-first analytics
● Evaluate other, add-on products that can improve application performance

Default improvements
1 min read

Cloudflare provides a variety of speed improvements by default.

DNS resolution
When your site is using Cloudflare, your site always benefits from Cloudflare’s lightning-fast
DNS resolution

Caching
When your DNS records are proxied through Cloudflare, Cloudflare caches certain types of
resources automatically (which improves application performance).

How does caching improve performance?

Caching is the process of storing copies of files in a cache, or temporary storage location, so
that they can be accessed more quickly.
When Cloudflare stores content in its cache, the request never needs to go to your
application or origin server, which reduces the number of requests and gets content to the
user more quickly.

Optimize caching
1 min read

Beyond default caching settings, you can further optimize your cache using different
Cloudflare settings.

A few ways to optimize Cloudflare caching include:

● Creating cache rules to customize the cache properties of specific HTTP requests.
● Enabling the Tiered Cache feature, which dramatically increases cache hit ratios.
● Reviewing our other various configuration options, which may vary based on your
plan and application setup.

Optimize analytics
2 min read

Web analytics let you measure user behavior - pageviews, sessions, and custom events - on
your application.

Cloudflare offers two ways to improve the privacy and performance of the way you gather
these analytics.

Cloudflare Web Analytics
If you want analytics without using third-party tools, check out Cloudflare Web Analytics.

Cloudflare Web Analytics provides free, privacy-first analytics for your website without
changing your DNS or using Cloudflare’s proxy. Cloudflare Web Analytics helps you
understand the performance of your web pages as experienced by your site visitors.

All you need to enable Cloudflare Web Analytics is a Cloudflare account and a JavaScript
snippet on your page to start getting information on page views and visitors. The JavaScript
snippet (also known as a beacon) collects metrics using the Performance API, which is
available in all major web browsers.

Setup

So long as your traffic is proxied through Cloudflare, setting up Web Analytics only involves a
few steps:
1. Log in to the Cloudflare dashboard
1. , and select your account.
2. Select the Analytics & Logs drop-down and choose Web Analytics.
3. Under Quick Actions, select Add a site.
4. Select a hostname from the drop-down menu > Done.

Access

Once you have enabled Web Analytics, you can review analytics at any time:

1. Log in to the Cloudflare dashboard
1. , and select your account.
2. Select the Analytics & Logs drop-down and choose Web Analytics.
3. Select your zone.
4. Review the various metrics provided by Cloudflare.

Notifications

Web Analytics uses Cloudflare’s Notification service. When enabled, Web Analytics sends
you a weekly report with aggregate visits, page views and median page load time for all your
sites, so you can monitor their performance.

To get started, add Web Analytics notification on your Cloudflare dashboard. Refer to
Cloudflare Notifications to learn more.

Cloudflare Zaraz
If you already use third-party tools on your website, check out Cloudflare Zaraz.

Cloudflare Zaraz gives you complete control over third-party tools and services for your
website, and allows you to offload them to Cloudflare’s edge, improving the speed and
security of your website. With Cloudflare Zaraz you can load tools such as analytics tools,
advertising pixels and scripts, chatbots, marketing automation tools, and more, in the most
optimized way.

Cloudflare Zaraz is built for speed, privacy, and security, and you can use it to load as many
tools as you need, with a near-zero performance hit.