diff --git a/taccsite_cms/static/site_cms/js/modules/setTargetForExternalLinks.js b/taccsite_cms/static/site_cms/js/modules/setTargetForExternalLinks.js
index b35b86ce3..d88cfbf24 100644
--- a/taccsite_cms/static/site_cms/js/modules/setTargetForExternalLinks.js
+++ b/taccsite_cms/static/site_cms/js/modules/setTargetForExternalLinks.js
@@ -4,6 +4,29 @@
  */
 export const DEFAULT_LINKS = document.querySelectorAll('body > :is(header, main, footer) a');
 
+/**
+ * Check if two hosts are effectively the same domain
+ * @param {string} linkHost - The host from the link
+ * @param {string} baseHost - The current page's host
+ * @param {string[]} subdomains - List of valid subdomains
+ * @returns {boolean}
+ */
+function isSameDomain(linkHost, baseHost, subdomains) {
+  // Direct match
+  if (linkHost === baseHost) return true;
+
+  // Link is to subdomain of base host
+  if (subdomains.some(subdomain => linkHost === `${subdomain}.${baseHost}`)) return true;
+
+  // Link is to root domain while we're on subdomain
+  if (subdomains.some(subdomain => 
+    baseHost.startsWith(`${subdomain}.`) && 
+    linkHost === baseHost.replace(`${subdomain}.`, '')
+  )) return true;
+
+  return false;
+}
+
 /**
  * Make links with absolute URLs open in new tab, and:
  * - add accessible markup
@@ -18,7 +41,10 @@ export default function findLinksAndSetTargets( links = DEFAULT_LINKS, opts = {
   shouldFilter: true,
 }) {
   const baseDocHost = document.location.host;
-  const baseDocHostWithSubdomain= `www.${ baseDocHost }`;
+  const standardSubdomains = ['www', 'pprd', 'prod', 'dev'];
+  const similarHosts = standardSubdomains.map(
+    subdomain => `${subdomain}.${baseDocHost}`
+  );
 
   if ( opts.shouldDebug ) {
     console.log({ links, opts });
@@ -33,7 +59,7 @@ export default function findLinksAndSetTargets( links = DEFAULT_LINKS, opts = {
 
     const isMailto = ( linkHref.indexOf('mailto:') === 0 );
     const isAbsolute = ( linkHref.indexOf('http') === 0 );
-    const isSameHost = ( link.host === baseDocHost || link.host === baseDocHostWithSubdomain );
+    const isSameHost = isSameDomain(link.host, baseDocHost, standardSubdomains);
     const shouldOpenInNewTab = ( ! isSameHost || isMailto );
 
     if (opts.shouldDebug) {