> ## Documentation Index
> Fetch the complete documentation index at: https://docs.apexlink.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Network looking glass and test files

## Overview

ApexLink runs a Looking Glass in each of its data centers, so you can test routing, latency and download speed from our network to yours — before you order or while troubleshooting.

* **Pre-sales evaluation**: measure latency, packet loss and throughput from each location to pick the best fit for your users.
* **Troubleshooting**: run a traceroute or MTR from our side to your IP to see whether an issue sits in our network, a transit carrier, or your local network.
* **Route lookup**: check the BGP path and AS path we use toward any prefix.

All Looking Glass tools are free to use and require no login.

## Looking Glass locations

| Location | Code | Looking Glass |
| :- | :- | :- |
| Hong Kong | `hk` | [hk.lg.apexlink.com](https://hk.lg.apexlink.com) |
| Singapore | `sg` | [sg.lg.apexlink.com](https://sg.lg.apexlink.com) |

The location code is also used in the speed test file URLs below.

## Supported diagnostics

On any Looking Glass page, pick a command and enter a target IP or hostname; results stream live in your browser.

| Command | What it does | When to use it |
| :- | :- | :- |
| `ping` | Sends ICMP echo requests and reports round-trip time and packet loss | Quick reachability and latency check |
| `traceroute` | Lists every hop between our network and the target | Spotting detours or sudden latency jumps |
| `mtr` | Continuous traceroute with per-hop loss and jitter statistics | Intermittent loss or peak-hour slowdowns |
| `bgp route` | Shows our best BGP path and AS path toward the target prefix | Confirming which upstream or exchange carries the traffic |
| `ping6` / `traceroute6` / `mtr6` | IPv6 versions of the commands above | Verifying IPv6 connectivity and routing |

**Tip:** test in both directions — from the Looking Glass to your IP, and from your machine to the Looking Glass hostname. Forward and return paths often differ, so a one-way test can mislead.

## Speed test files

Each location hosts test files for measuring download speed. Replace `{code}` with the location code from the Looking Glass locations table (for example, `hk`).

| Size | URL |
| :- | :- |
| 100 MB | `https://{code}.lg.apexlink.com/speedtest/100MB.test` |

A single TCP connection is limited by window size and latency. To test full line rate, use a multi-connection tool such as `aria2c -x 8`.

## Reading results and opening a ticket

Many results that look like problems are normal. Check this table before opening a ticket.

<table>
  <colgroup>
    <col width="277" />

    <col width="234" />

    <col width="325" />
  </colgroup>

  <thead>
    <tr>
      <th>What you see</th>
      <th>Likely cause</th>
      <th>Action needed</th>
    </tr>
  </thead>

  <tbody>
    <tr>
      <td>A middle hop shows `* * *` or high loss, but later hops are clean</td>
      <td>That router rate-limits ICMP replies</td>
      <td>No — only the final hop matters</td>
    </tr>

    <tr>
      <td>Latency jumps at one hop and stays high for every hop after</td>
      <td>Subsea link or a routing detour</td>
      <td>Depends on the increase; send us the result if unsure</td>
    </tr>

    <tr>
      <td>Sustained loss at the final hop</td>
      <td>Congestion at the target host or its upstream</td>
      <td>Yes</td>
    </tr>

    <tr>
      <td>Download speed far below your plan</td>
      <td>Single-connection limit, Wi-Fi, or peak-hour congestion</td>
      <td>Retest with multiple connections over a wired link first</td>
    </tr>
  </tbody>
</table>

If you still need help, include the following in your ticket so our engineers can act quickly:

1. Your public IP address
2. An MTR from the Looking Glass to your IP (at least 100 packets)
3. An MTR or traceroute from your machine to the same Looking Glass hostname
4. When the issue occurred (with time zone) and whether it is ongoing

Paste results as text rather than screenshots, so they can be copied and compared.


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