06. Connecting a Custom Domain

1. Overview

Purchased securenomad.kr from Gabia (a Korean domain registrar) and connected the subdomain wiki.securenomad.kr to the GitHub Pages site.

Visitor ─▶ wiki.securenomad.kr
              │  (Gabia DNS: CNAME)
              ▼
          inseokjeon-sec.github.io   (GitHub Pages)
              │
              ▼
          Deployed output (build) of the SecureNomad repository

Item	Before	After
Site URL	`https://inseokjeon-sec.github.io/SecureNomad/`	`https://wiki.securenomad.kr`
`baseUrl`	`/SecureNomad/`	`/`
HTTPS	GitHub default certificate	Certificate issued automatically by GitHub (Let's Encrypt)

2. Choosing the connection method

DNS instead of forwarding

Method	Behavior	Result
URL redirect (forwarding)	Redirects my domain to the github.io URL	The address bar changes to github.io
URL masking (frame)	Shows the site inside an iframe on my domain	HTTPS issues, poor search visibility, fixed URL while navigating
DNS (CNAME)	My domain points directly to GitHub Pages servers	Site served on my domain, free HTTPS

→ Chose DNS, the method officially supported by GitHub Pages.

Subdomain

Type	Example	Records needed
Subdomain (chosen)	`wiki.securenomad.kr`	1 CNAME
Apex domain	`securenomad.kr`	4 A records (+ www CNAME)

Simpler to configure
The apex domain stays available for other uses such as a main homepage

3. Buying the domain (Gabia)

Item	Setting	Reason
WHOIS privacy	On	Hides name, address, and contact details
Auto-renewal	On	Expiration would take the site down and let others register the domain
Hosting, forwarding, email add-ons	Not used	GitHub Pages provides hosting and HTTPS for free
Name servers	Keep Gabia defaults (`ns.gabia.co.kr`)	Only a few records are needed, so no separate DNS is required

:::tip Check the renewal price Check the renewal price from year 2 onward, not just the first-year discount. :::

4. Verifying domain ownership on GitHub (TXT)

Why it matters

:::danger Subdomain Takeover If the CNAME record remains in DNS after GitHub Pages is disconnected, someone else can register the same domain on their own GitHub Pages repository and serve arbitrary content on my subdomain. Verifying the domain on my GitHub account ensures that only repositories in my account can use it. :::

Steps

Top-right profile picture → Settings (account settings) on GitHub
Left menu Pages → Add a domain
Enter the apex domain securenomad.kr (verify the apex domain even when using a subdomain)
Add the TXT record that GitHub provides to Gabia DNS

Type	Host	Value
TXT	`_github-pages-challenge-<username>`	Verification value issued by GitHub

Click Verify on GitHub → confirm Verified

caution

The verification value is issued per account, so it is not published in documents or screenshots.

5. Adding a CNAME record in Gabia DNS

My Gabia → Domains → manage securenomad.kr → DNS management tool

The DNS management screen:

Section	Used
DNS settings → [Edit records]	Yes (add TXT and CNAME)
Domain connection	No (for Gabia hosting)
Forwarding	No (redirect / masking)
Web parking / Mobile parking	No

Add the record

Click [Edit records] next to DNS settings
Click [Add record] → fill in a new row
Click the row's [OK] → [Save] at the bottom

Type	Host	Value	TTL
TXT	`_github-pages-challenge-<username>`	(verification value)	600
CNAME	`wiki`	`inseokjeon-sec.github.io.`	600

Enter only wiki as the host (Gabia appends .securenomad.kr automatically)
Do not add a path such as /SecureNomad to the value
The trailing dot (.) marks the end of the domain. Remove it and retry if you get a format error
Keep the existing TXT record

6. Checking DNS propagation

nslookup wiki.securenomad.kr

Example of a correct result:

Name:    inseokjeon-sec.github.io
Addresses:  185.199.108.153
            185.199.109.153
            185.199.110.153
            185.199.111.153
Aliases:  wiki.securenomad.kr

If Aliases shows my domain and Name shows the github.io address, the CNAME is active
Propagation can take from a few minutes to a few hours

7. Updating project files

static/CNAME (new)

A file without an extension containing a single line with the domain.

static/CNAME
wiki.securenomad.kr

Files in static/ are copied to the root of build/ → deployed as build/CNAME so GitHub Pages recognizes the domain.

docusaurus.config.js

docusaurus.config.js
  url: 'https://wiki.securenomad.kr',
  baseUrl: '/',

Field	Reason for change
`url`	Canonical site URL (used for the sitemap, share links, etc.)
`baseUrl`	Served from the domain root, so `/SecureNomad/` → `/`

:::warning If baseUrl is not changed CSS and JS files are requested from /SecureNomad/..., and the page renders broken. :::

Apply

Check for errors with npm run build, then Commit → Push origin in GitHub Desktop.

8. Repository Pages settings

Repository SecureNomad → top Settings → left Pages

Under Build and deployment, enter wiki.securenomad.kr in Custom domain → Save
Confirm DNS check successful
Check Enforce HTTPS

:::info Enforce HTTPS is disabled The checkbox stays grayed out until the certificate is issued. Check it once it becomes available (a few minutes to up to a day). :::

9. Points that were confusing

There are two Settings pages

Location	Purpose
Profile picture → Settings → Pages (account)	Domain ownership verification (TXT, Verify)
Repository → Settings → Pages (repository)	Custom domain, Enforce HTTPS

Order of work

① Buy the domain
② Verify the domain in account Settings (TXT)
③ Add the CNAME in Gabia
④ Confirm propagation with nslookup
⑤ Update CNAME file + config → Push
⑥ Save Custom domain in repository Settings → Enforce HTTPS

:::caution Why the order matters If ⑤ and ⑥ are done before DNS propagates (④), the github.io URL redirects to a domain that is not connected yet, and the site becomes temporarily unreachable. :::

10. Result

Site URL: https://wiki.securenomad.kr
https://inseokjeon-sec.github.io/SecureNomad/ redirects to the new domain automatically
HTTPS enabled (padlock icon)

Checklist

Account Settings → Pages: securenomad.kr Verified
Gabia DNS: TXT and CNAME (wiki) records registered
nslookup shows github.io
static/CNAME, url, baseUrl updated and pushed
Repository Settings → Pages: DNS check successful
Enforce HTTPS checked
https://wiki.securenomad.kr reachable

1. Overview​

2. Choosing the connection method​

DNS instead of forwarding​

Subdomain​

3. Buying the domain (Gabia)​

4. Verifying domain ownership on GitHub (TXT)​

Why it matters​

Steps​

5. Adding a CNAME record in Gabia DNS​

Menu location​

Add the record​

6. Checking DNS propagation​

7. Updating project files​

static/CNAME (new)​

docusaurus.config.js​

Apply​

8. Repository Pages settings​

9. Points that were confusing​

There are two Settings pages​

Order of work​

10. Result​

Checklist​