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Outbyte PC Repair FREERepair Windows errors before they cause bigger problemsFix Now →Outbyte Driver Updater FREEFix the driver behind crashes, sound loss and screen glitchesFind Drivers →When you open bbc.com, the browser may need to find the site’s network address, establish a connection, secure it for HTTPS, and request the page. On a new HTTPS connection that uses TCP, one of the setup steps is a three-message handshake: SYN, SYN-ACK, then ACK. That is not three packets for the whole page load, and the browser may skip or reuse some setup work if it already has cached DNS information or an open connection.
What happens when you type a website address into your browser?
The sequence below is a common model for a new HTTPS visit over TCP, not a trace of BBC.com’s live infrastructure. A browser’s actual path depends on what it already knows and which protocols the site and browser use.
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- Resolve the name. The browser needs an IP address associated with the hostname
bbc.com. It uses DNS information, which may already be cached; the browser does not necessarily perform a fresh lookup on every navigation. The resolver path can vary, and a browser does not necessarily contact an authoritative DNS server directly. MDN’s web primer introduces how browsers use hostnames and addresses. - Establish a TCP connection if one is needed. For a new TCP connection, the client sends SYN, the server replies with SYN-ACK, and the client sends ACK. This three-message handshake establishes the connection. It occurs after DNS lookup and before TLS when creating a new secure TCP connection. MDN’s TCP handshake glossary describes this order.
- Negotiate HTTPS security if needed. TLS negotiates security parameters, authenticates the server, and establishes session keys so the connection can be protected. The details depend on the TLS version and whether the browser can resume a prior session; there is no single message count that applies to every visit. See MDN’s TLS guide.
- Request the page. Once a usable connection is ready, the browser sends an HTTP request, commonly a
GETfor the document. The server responds, and the browser processes the returned page and requests any additional resources it needs. MDN’s browser-loading guide explains this sequence.
What does the “three packets” part mean?
It means the three messages in a TCP connection setup: SYN, SYN-ACK, and ACK. It does not count every packet involved in loading a website, including TLS traffic, the HTTP request and response, or later resources. The three-message sequence applies when the browser creates a new TCP connection; an existing connection can be reused instead.
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Why can the setup add delay?
On an initial request, DNS resolution, connection establishment, and secure negotiation can each contribute time before page data arrives. A later request may need less setup if DNS information is cached, the connection remains open, or TLS session resumption is available. The amount of time saved or spent depends on network conditions and what can be reused; there is no universal delay or fixed number of round trips for every visitor.
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HTTP/3 is another reason not to treat the TCP sequence as universal: it uses a different transport path. The TCP-handshake explanation is specifically for a new secure connection over TCP.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.How to inspect the timing in your browser
Browser navigation timing records milestones for a particular navigation. MDN documents timing fields and formulas for estimating DNS lookup, TCP connection, and TLS-related durations in Navigation timing. Those measurements describe the browser session you examined, not a guaranteed path or delay for every BBC.com visitor.
- Compare DNS lookup time, connection time, secure-connection time, request start, and response start.
- Interpret missing or very short setup intervals cautiously: cached DNS, connection reuse, or resumption can change which work is repeated.
- Do not read one browser’s timing as a measurement of all users or as a live infrastructure trace for BBC.com.
For additional background on how network delay affects page loading, see MDN’s guide to latency.
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