DNS

Time spent resolving the hostname to an IP address.

Only the first request to a given host pays this; every later request to the same host reuses the answer for as long as the DNS record's TTL allows, so it shows as zero. A large DNS time that keeps recurring on the same host across many requests usually means the OS or browser DNS cache is being bypassed, not that resolution is slow every single time.

Other timing phases

• Blocked — Time spent queued before the browser could even open a connection for this request.
• Connect — Time spent establishing the TCP connection, including the TLS handshake for HTTPS.
• SSL / TLS handshake — The portion of connect time spent negotiating TLS, shown separately for inspection.
• Send — Time spent writing the request onto the wire.
• Wait (TTFB) — Time between the request finishing transmission and the first byte of the response arriving.
• Receive — Time spent reading the response body after the first byte arrived.