**Yes, this is expected behavior in most cases.** Here's a clear breakdown of your questions based on how Plesk manages IIS Application Pools on Windows.
### 1. What is the exact purpose of the reseller-level IIS Application Pool?
The pool you see in **Tools & Utilities → IIS Application Pool** (named something like `<ResellerName>(client)(pool)`) is a **reseller/container-level pool** that Plesk creates when the reseller has dedicated IIS pool capabilities enabled in their plan or customization.
Its main purposes are:
- To provide a **shared isolation container** for all (or many) subscriptions/customers under that reseller.
- To allow the reseller (or admin) to apply global settings like CPU limits, worker processes, idle timeout, recycling, 32/64-bit mode, etc., that can apply across their customers.
- It acts as a parent or grouping mechanism for the reseller's hosting resources.
It is **not** the same as the per-subscription/dedicated pools that individual customers see under their **Websites & Domains → Dedicated IIS Application Pool for Website**.
### 2. Should stopping this reseller-level pool affect all websites under the reseller?
**Not necessarily in a hard-stop way**, and this matches what you're seeing.
- Stopping the reseller-level pool in **Tools & Utilities** primarily affects the **global/shared settings** for the reseller's pool and any child elements tied directly to it.
- Individual **subscriptions/customers** often run in their own **dedicated per-subscription application pools** (even if nested under or associated with the reseller pool). These can continue running independently.
- Plesk's architecture allows subscriptions to have their own isolated pools for better stability and security. Stopping the "parent" reseller pool does **not** automatically stop or recycle the child pools/websites.
This is why your customer-level test (stopping their own pool) correctly shows **503 Service Unavailable**, but the reseller-level stop does not.
### 3. Is the websites still working after stopping the reseller pool expected behavior or an issue?
**This is expected behavior** in standard Plesk configurations with dedicated pools enabled per subscription or package. It is **not a bug** — it's how isolation works.
The command you ran (`appcmd list app /apppool.name:"<ResellerName>(client)(pool)"`) returning no output confirms that **no applications/sites are directly bound to that reseller-level pool**. The actual websites are using separate dedicated pools.
### 4. How to identify which websites/subscriptions are using this reseller-level IIS Application Pool?
- **In IIS Manager** (best way — RDP to the server):
- Open **IIS Manager** → **Application Pools**.
- Look at the **Application Pool** column for each site under the reseller.
- Check the pool names (they often include the subscription/domain name or customer ID).
- **Via command line** (run in elevated Command Prompt):
```cmd
%windir%\system32\inetsrv\appcmd list sites
%windir%\system32\inetsrv\appcmd list app
%windir%\system32\inetsrv\appcmd list apppool
```
This will show mappings between sites, apps, and pools.
- In Plesk: Check each subscription's **Websites & Domains → Dedicated IIS Application Pool** status.
### 5. Permission or configuration issue?
Possibly a configuration (more likely than permissions):
- Confirm whether **Dedicated IIS Application Pool** is enabled at the **service plan / reseller customization / individual subscription** level. If per-subscription dedicated pools are active, the reseller pool is more of a settings container.
- Check **Permissions** in the reseller's plan/customization for "IIS application pool management".
- Resync subscriptions if needed (Subscriptions → select → Sync with plan).
### Recommendations
- To properly take websites offline for the entire reseller: **Suspend the reseller account** (or individual subscriptions). This is the cleanest way.
- For maintenance: Stop/recycle pools at the **subscription level** or directly in IIS Manager.
- If you want one big pool for all under the reseller: Adjust the global settings or service plans to use fewer dedicated pools.