---
title: "External File image banners"
description: "Point a banner at an image hosted on your own server or CDN — the Image creative URL, the Banner link on video placements, the click-through URL and Serve from our server with Refresh copy — step by step."
type: "howto"
audience: [network-manager, advertiser]
keywords: [external file, image banner, image creative URL, banner link, serve from our server, refresh copy, hot-linked image, CDN image, click URL]
ui_path: "Account → Advertisers → campaign → Add new banner"
---

Fetch the complete documentation index at: https://epom.com/ad-server/docs/llms.txt. Use this file to discover all available pages before exploring further. Append .md to any documentation page URL to get its markdown version.

# External File image banners

An **External File** banner is an image that stays on your server or CDN: you give Epom the URL,
and every impression loads it from there — unless you tick **Serve from our server**, which
keeps the URL but serves Epom's stored copy. The click URL, ad unit, title and target are the
same as on a [Local File](https://epom.com/ad-server/docs/guides/advertising/banner-image-local-file.md) banner; both are compared on
[Image banners](https://epom.com/ad-server/docs/guides/advertising/banner-image.md).

**Example.** Summit Ridge Digital keeps its 300×250 creative on its own CDN and swaps the file
there every week. One External File banner with the CDN address in **Image creative URL** and the
landing page in **URL** follows every swap; with **Serve from our server** ticked it serves
Epom's copy instead, and **Refresh copy** picks up the new file.

## Typical scenarios

| You want | Set | Where |
|---|---|---|
| A creative that lives on the client's CDN and changes there | **External File**, **Image creative URL** — hot-linked on every impression | Add new banner → External File |
| The client's CDN image, but served from Epom (no hot-linking, no CDN outages) | External File + **Serve from our server**; **Refresh copy** when the file changes behind the same URL | Under the creative URL field |
| An image creative on a video placement | External File with **Banner link** (Video replaces Image creative URL); Epom fetches it on save to confirm it is an image | Add new banner → Video placement |

## Step by step

### External File

1. **Add new banner** → the placement type → set **Banner type** to *External File*.
2. Enter the **Image creative URL** — where the image is hosted. Required, no spaces. On a
   **Video** placement the field is called **Banner link** instead, and Epom fetches it on save to
   confirm it is an image (*Cannot get an image file by this link* otherwise).
3. Enter the click-through **URL**, pick the **Ad unit**, optionally Title and Target. The two
   URL fields are easy to mix up: **Image creative URL** is the picture, **URL** is where the
   click goes.
4. Optionally tick **Serve from our server**, under the creative URL field, to have Epom download
   the image and serve its own copy while the URL stays as typed.
5. **Save**. With the box ticked, **Served from our copy** lists the stored file; **Refresh copy**
   downloads the link again for a file that changed behind the same address — and also saves any
   other edit on the form.

   ![External File banner with both URL fields](https://epom.com/docs-images/ad-server/banner-image/external-file-fields.webp)

## Caveats and exceptions

**Serve from our server downloads on save and when the URL changes.** Clearing the box serves
the link again and drops the copy. A failed download blocks the save, with the reason on the
creative URL field.

The caveats that apply to both flavours — who can do this, the two messages after a successful
save, the size mismatch, the network-wide file limit, linking — are on
[Image banners](https://epom.com/ad-server/docs/guides/advertising/banner-image.md#caveats-and-exceptions).

## Not working?

| Symptom | Check | Where |
|---|---|---|
| *Incorrect content type of the creative…* after Save | External URL could not be fetched or is not an image; saved anyway (fatal on Video) | The **Image creative URL** |
| *Cannot get an image file by this link* | Video placement **Banner link** is not an image | The link |
| Old image still served after the CDN file changed | **Serve from our server** holds the copy | **Refresh copy** |

The rest of the list — the file limit, the size and URL messages, **Not serving** — is on
[Image banners](https://epom.com/ad-server/docs/guides/advertising/banner-image.md#not-working).

## Reference

Every field, what the form and the server check and the API parameters (`imageBannerLink`,
`hostExternalFiles`, `refreshHostedFiles`) are on [Image banners](https://epom.com/ad-server/docs/guides/advertising/banner-image.md#reference).

## Related

- [Image banners (Local File and External File)](https://epom.com/ad-server/docs/guides/advertising/banner-image.md)
- [Local File image banners](https://epom.com/ad-server/docs/guides/advertising/banner-image-local-file.md)
- [Banner types — decision guide](https://epom.com/ad-server/docs/guides/advertising/banners-overview.md)
- [Banner types reference](https://epom.com/ad-server/docs/reference/banner-types.md)