Country Codes in IP Geolocation and Geo-Targeting

Country Codes and Geolocation

IP geolocation maps an IP address to a geographic location, and the country code is the most reliable piece of data returned. City and region data can be inaccurate, but country-level geolocation is typically 95-99% accurate.

Geolocation Database Response

A typical GeoIP lookup returns:

{
  "ip": "203.0.113.42",
  "country_code": "JP",
  "country_name": "Japan",
  "region_code": "JP-13",
  "region_name": "Tokyo",
  "city": "Shibuya",
  "postal_code": "150-0002",
  "latitude": 35.6617,
  "longitude": 139.7041,
  "timezone": "Asia/Tokyo",
  "isp": "NTT Communications"
}

Common Geolocation Use Cases

1. Content localization — Show content in the user's language based on country
2. Pricing — Display prices in local currency
3. Compliance — Block access from sanctioned countries
4. Licensing — Restrict media content by region (geo-fencing)
5. Fraud detection — Flag mismatches between billing country and IP country
6. Ad targeting — Serve region-specific advertisements
7. CDN routing — Direct users to the nearest data center

Server-Side Geolocation

// Using MaxMind GeoIP2 in Node.js
const Reader = require('@maxmind/geoip2-node').Reader;

async function getCountry(ip) {
  const reader = await Reader.open('/path/to/GeoLite2-Country.mmdb');
  const response = reader.country(ip);
  return {
    code: response.country.isoCode,    // "JP"
    name: response.country.names.en,    // "Japan"
    isEU: response.country.isInEuropeanUnion // false
  };
}

Client-Side Geolocation Headers

Many CDNs and reverse proxies add geolocation headers:

CF-IPCountry: JP          (Cloudflare)
X-Vercel-IP-Country: JP   (Vercel)
X-Amz-Cf-IPCountry: JP   (CloudFront — custom)
X-Country-Code: JP        (Custom header convention)

Geo-Fencing Patterns

// Block access from specific countries
const BLOCKED = ['KP', 'IR', 'CU', 'SY'];

function checkAccess(countryCode) {
  if (BLOCKED.includes(countryCode)) {
    return { allowed: false, reason: 'Service unavailable in your region' };
  }
  return { allowed: true };
}

// EU-specific compliance
function requiresCookieConsent(countryCode) {
  const EU_EEA = ['AT','BE','BG', /* ... */,'SE','IS','LI','NO'];
  return EU_EEA.includes(countryCode);
}

Accuracy Considerations

Level	Typical Accuracy
Country	95-99%
Region/State	80-90%
City	60-80%
Postal code	50-70%

VPNs, proxies, and mobile networks can reduce accuracy. Always provide a way for users to manually set their country.