Delta Speed Test — BDIX and international speed, measured separately

Every internet connection in Bangladesh really has two speeds. Traffic that stays inside the country over BDIX peering is fast and cheap for your ISP to carry. Traffic that leaves the country crosses their international (IIG) capacity, which is usually a fraction of it. Most speed tests show you one number and leave you guessing which one you got.

Delta measures both in one run and reports the gap between them, so you can see how much of the speed you are paying for actually reaches the wider internet.

What it measures

• Local (BDIX) — download and upload against a server inside Bangladesh.
• Raw (international) — the same test against a server abroad, with a choice of Singapore, Mumbai or Tokyo.
• Ping and jitter — latency and how steady it is, for each path.

Why local and international speeds differ in Bangladesh

BDIX is the Bangladesh Internet Exchange. When your ISP peers there, traffic between you and other members never leaves the country, so it runs at close to your full port speed. Anything beyond that has to travel over submarine cable capacity your ISP buys by the megabit, which is why a connection that benchmarks at several hundred megabits locally can still be slow on YouTube or a game server hosted overseas.

IP and NAT tools

Delta also tells you what kind of address your ISP has given you and whether the internet can reach you. If you are behind carrier-grade NAT you share one public address with other subscribers, which means port forwarding does not work: torrents will not seed, game hosting fails, and you cannot reach your own NAS from outside.

• Inbound reachability test — a server in Singapore tries to open real TCP connections back to your address. Nothing needs to be open for this to work: a refused connection still proves traffic from the internet reaches you, which is exactly what carrier NAT takes away.
• Shared or public IP check — detects carrier NAT address space and reads your reverse DNS for the names ISPs use for shared and dynamic addresses.
• Specific port check — if you have forwarded a port for seeding or hosting, test that it is actually reachable.

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