关于确认Ubuntu仓库下载来源为美国服务器的技术问询

Hey Steve, totally get your confusion here—seeing us.archive.ubuntu.com resolve to a UK IP does feel counterintuitive! Let me break this down and show you how to lock in US-based servers for your Ubuntu repo downloads.

First off, the reason behind the unexpected DNS resolution is that Ubuntu's archive subdomains like us.archive.ubuntu.com use anycast routing. This means the DNS will point you to the geographically closest server in Ubuntu's global network, but sometimes network routing quirks or your ISP's settings can cause it to pick a server outside the expected region. The "us" label is more of a hint for the anycast system, not a strict guarantee of a US-based server.

Here are concrete steps to make sure you're downloading from US servers:

• Switch to a specific US-hosted mirror
  Instead of relying on the generic anycast subdomain, use a direct US mirror. Here's how:

  1. Open your APT sources file with sudo nano /etc/apt/sources.list
  2. Replace every instance of archive.ubuntu.com or us.archive.ubuntu.com with a confirmed US mirror, like mirror.us.leaseweb.net/ubuntu or us.mirrors.cicku.com/ubuntu
  3. Save the file (Ctrl+O, then Enter) and exit nano (Ctrl+X), then run sudo apt update to apply the changes

• Verify the server's location
  To double-check you're connected to a US server:

  1. Run ping us.archive.ubuntu.com (or your chosen mirror) to get the resolved IP address
  2. Use whois <IP_ADDRESS> (replace <IP_ADDRESS> with the one you got) and look for the Country field in the output—it should show US if it's a US-based server. If not, switch to one of the specific mirrors mentioned above.

• Automatically find the fastest US mirrors
  You can use a tool to generate a sources list with the fastest US mirrors:

  1. Install the tool with sudo apt install netselect-apt
  2. Run sudo netselect-apt -c US—this will scan US mirrors, pick the fastest ones, and replace your existing sources.list file. Just confirm the changes when prompted.

That should resolve your issue and ensure your Ubuntu repo downloads are coming from US-based servers. Let me know if you hit any snags while setting this up!

备注：内容来源于stack exchange，提问作者stevej