Akamai Web Performance flashcards

32 cards. Read the term and the definition here. The deck at the top of this page is optional.

Round-trip time (RTT)

The time for a packet to travel to a destination and back. Each new connection adds handshake RTTs before any content can be delivered.

HTTP/2 multiplexing

Sends many concurrent request streams over a single TCP connection, eliminating per-request connection setup but sharing TCP head-of-line blocking.

QUIC and HTTP/3

A UDP-based transport with independent streams so packet loss on one stream does not stall others, plus faster connection resumption.

Anycast routing

Advertising the same IP address from many locations so BGP routes each user to a topologically nearby point of presence.

Cache hit ratio

Cache hits divided by total requests. Higher ratios mean more content served from edge and less origin load.

Time to first byte

Elapsed time from request initiation to the first response byte, combining DNS, connection setup, server processing, and network latency.

Property version

An immutable snapshot of a property's rules and behaviors. It must be activated on a network before it affects live traffic.

Rule matching order

Rules evaluate top-down and the first matching rule wins unless child rules or fallthrough criteria are configured to continue evaluation.

Behaviors versus match criteria

Match criteria decide when a rule applies, such as hostname or path; behaviors decide what happens, such as caching or origin selection.

Property Manager API

A REST interface for creating properties, editing versions and rules, managing hostnames, and triggering asynchronous activations.

Activation rollback

Restoring prior behavior by activating an earlier property version on the network, since live configuration cannot be edited in place.

Include rules

Reusable rule sets shared across properties; the including property can override specific behaviors where it defines them.

s-maxage directive

A Cache-Control directive setting freshness lifetime for shared caches such as CDN edges, overriding max-age for those caches.

Cache key composition

The set of request attributes that identify a cached object, typically hostname, path, query string, and selected headers or cookies.

stale-while-revalidate

Allows a cache to serve stale content for a defined window while asynchronously fetching a fresh copy from the origin.

stale-if-error

Permits serving stale cached content when the origin returns an error or is unreachable, improving availability during incidents.

Tag-based purge

Invalidation using cache tags or CP codes rather than enumerating individual URLs, useful when content has many URL variants.

Tiered distribution

Inserts a parent cache tier between edge servers and origin, raising edge hit ratio and shielding the origin from repeated misses.

Vary header impact

Varying on high-cardinality headers like User-Agent or Cookie fragments the cache and sharply lowers hit ratio.

Render-blocking resources

CSS and synchronous scripts in the head delay first paint. Defer or async scripts and inline critical CSS to shorten the critical path.

Preload versus prefetch

Preload fetches resources needed for the current navigation at high priority; prefetch fetches likely future resources at low priority.

Preconnect hint

Opens DNS, TCP, and TLS to an origin ahead of need, removing setup latency from the critical request path.

Edge compute

Running logic such as personalization, header rewriting, or response assembly at the edge to avoid origin round trips.

Brotli compression

A compression algorithm that generally outperforms gzip on text assets; avoid applying it to already-compressed media files.

Cumulative layout shift

A Core Web Vital measuring unexpected visual movement of page elements, often caused by images without reserved dimensions.

Synthetic versus RUM

Synthetic tests run scripted checks from fixed locations; real user monitoring captures actual user experiences across devices and networks.

Waterfall breakdown

Splits request timing into DNS, connect, TLS, TTFB, and download phases to identify whether latency is network, edge, or origin.

Staging versus production activation

Staging uses a separate network and hostname for validation; production activation serves live traffic and should follow staging verification.

DataStream logs

Per-request log delivery that lets teams correlate traffic shifts with purges, activations, or origin errors.

Hit ratio drop causes

Common causes include cache-key changes, purge storms, query-string variance, and new cookie or header variation in requests.

HSTS policy

A response header instructing browsers to use HTTPS only for a domain, preventing protocol downgrade and mixed-content exposure.

Origin shielding

A parent or shield tier that absorbs traffic so the origin sees fewer requests and is less exposed during spikes or attacks.