diff --git a/README.md b/README.md
index 2f60cdc..bd70828 100644
--- a/README.md
+++ b/README.md
@@ -1,11 +1,29 @@
 # Vercel Dynamic DNS
 
-Script for exposing local server with [Vercel DNS](https://vercel.com/docs/custom-domains). It runs every 15 minutes, checking current IP address and updates DNS records for your domain.
+Simple script for exposing a local server with [Vercel DNS](https://vercel.com/docs/custom-domains).
+It runs on CRON, checking the current IP address and updating DNS records for your domain.
 
 ## Installation
 
-1. Download
-2. Move `dns.config.example` into `dns.config`
-3. Edit config
-4. Open cron settings `crontab -e`
-5. Add this line `*/15 * * * * /home/username/vercel-ddns/dns-sync.sh`
+1. Ensure that you have [jq](https://github.com/jqlang/jq) installed
+2. Download `dns-sync.sh`
+3. Move `dns.config.example` to `dns.config`
+4. Edit the configuration variables as required
+5. Open the cron settings using the command `crontab -e`
+6. Add the following line to the cron job: `*/15 * * * * /path-to/vercel-ddns/dns-sync.sh`
+
+## Usage example
+
+```sh
+# Creating
+➜  ./dns-sync.sh
+Updating IP: x.x.x.x
+Record for SUBDOMAIN does not exist. Creating...
+🎉 Done!
+
+# Updating
+➜  ./dns-sync.sh
+Updating IP: x.x.x.x
+Record for SUBDOMAIN already exists (id: rec_xxxxxxxxxxxxxxxxxxxxxxxx). Updating...
+🎉 Done!
+```
diff --git a/dns-sync.sh b/dns-sync.sh
index eea6a45..a25b74d 100755
--- a/dns-sync.sh
+++ b/dns-sync.sh
@@ -1,21 +1,103 @@
 #!/bin/bash
 
+# Vercel Dynamic DNS
+# https://github.com/iam-medvedev/vercel-ddns
+
 source ./dns.config
 
-# 1. Get current IP
-IP=$(curl -s http://whatismyip.akamai.com/)
-echo "$IP"
-
-# 2. Create/update DNS record
-curl -X POST "https://api.vercel.com/v2/domains/$DOMAIN_NAME/records" \
-  -H "Authorization: Bearer $VERCEL_TOKEN" \
-  -H "Content-Type: application/json" \
-  -d '{
-  "name": "'$SUBDOMAIN'",
-  "type": "A",
-  "value": "'$IP'",
-  "ttl": 60
-}'
-
-echo ''
+# Check if jq is installed
+if ! command -v jq >/dev/null; then
+  echo "Error: 'jq' is not installed. Please install 'jq' to run this script."
+  exit 1
+fi
+
+# Returns current IP
+get_current_ip() {
+  local ip
+  ip=$(curl -s http://whatismyip.akamai.com/)
+  echo $ip
+}
+
+# Function to check if subdomain exists
+check_subdomain_exists() {
+  local subdomain="$1"
+  local response
+  response=$(curl -sX GET "https://api.vercel.com/v4/domains/$DOMAIN_NAME/records" \
+    -H "Authorization: Bearer $VERCEL_TOKEN" \
+    -H "Content-Type: application/json")
+
+  local record_id
+  record_id=$(echo "$response" | jq -r ".records[] | select(.name == \"$subdomain\") | .id")
+  if [[ -n "$record_id" ]]; then
+    # Return record ID if exists
+    echo "$record_id"
+  else
+    # Subdomain does not exist
+    return 1
+  fi
+}
+
+# Updates dns record
+update_dns_record() {
+  local ip="$1"
+  local record_id="$2"
+  local response
+  response=$(curl -sX PATCH "https://api.vercel.com/v1/domains/records/$record_id" \
+    -H "Authorization: Bearer $VERCEL_TOKEN" \
+    -H "Content-Type: application/json" \
+    -d '{
+      "comment": "vercel-ddns",
+      "name": "'$SUBDOMAIN'",
+      "type": "A",
+      "value": "'$ip'",
+      "ttl": 60
+    }')
+
+  # Check for errors in the response
+  if [[ "$response" == *"error"* ]]; then
+    local error_message
+    error_message=$(echo "$response" | jq -r '.error.message')
+    echo "⚠️ Error updating DNS record: $error_message"
+    exit 1
+  fi
+}
+
+# Creates dns record
+create_dns_record() {
+  local ip="$1"
+  local response
+  response=$(curl -sX POST "https://api.vercel.com/v4/domains/$DOMAIN_NAME/records" \
+    -H "Authorization: Bearer $VERCEL_TOKEN" \
+    -H "Content-Type: application/json" \
+    -d '{
+      "comment": "vercel-ddns",
+      "name": "'$SUBDOMAIN'",
+      "type": "A",
+      "value": "'$ip'",
+      "ttl": 60
+    }')
+
+  # Check for errors in the response
+  if [[ "$response" == *"error"* ]]; then
+    local error_message
+    error_message=$(echo "$response" | jq -r '.error.message')
+    echo "⚠️ Error creating DNS record: $error_message"
+    exit 1
+  fi
+}
+
+# Get current IP
+ip=$(get_current_ip)
+echo "Updating IP: $ip"
+
+# Check if subdomain exists
+record_id=$(check_subdomain_exists "$SUBDOMAIN")
+if [[ -n "$record_id" ]]; then
+  echo "Record for $SUBDOMAIN already exists (id: $record_id). Updating..."
+  update_dns_record "$ip" "$record_id"
+else
+  echo "Record for $SUBDOMAIN does not exist. Creating..."
+  create_dns_record "$ip"
+fi
+
 echo "🎉 Done!"
diff --git a/dns.config.example b/dns.config.example
index e53e4f9..90cc8e0 100644
--- a/dns.config.example
+++ b/dns.config.example
@@ -1,5 +1,10 @@
-# Get token here https://vercel.com/account/tokens
+#!/bin/bash
+
+# Get the token from https://vercel.com/account/tokens
 VERCEL_TOKEN=""
 
-# Your domain/subdomain
+# Domain name (e.g. example.com)
 DOMAIN_NAME=""
+
+# Subdomain to update (note: use an empty string for the root record)
+SUBDOMAIN=""