When the domain burn rate β = λdisc/λintro exceeds 1, time-average availability is bounded by A ≤ 1/β regardless of rotation speed µ, endpoint count n, or domain buffer kmax (Theorem 2). Rotation speed µ appears only in the address factor, which redundancy already saturates, and is entirely absent from the binding domain layer — proving that 'rotate faster' is categorically the wrong design lever under a domain-filtering censor.

Address blocking is a losing strategy for the censor: with n=8 endpoints and µ/λa = 1 (discovery as fast as rotation), address-denial probability falls below 10^-2, and even when the censor discovers twice as fast as the defender rotates (µ/λa = 0.5), 7 endpoints keep address denial below 10^-2 (Lemma 1, Figure 1). The collateral budget γ means the censor cannot even block all addresses it discovers, and Corollary 1 gives the explicit threshold: n ≥ ln(1/ε) / ln((λa+µ)/λa) endpoints suffice for any target ε.

§5, §8.1, §8.10, Lemma 1, Corollary 1, Figure 1 evaluation

Correlated domain burns (e.g., registrar takedowns) collapse the sustainability frontier far more than mean burn rate alone: the interval frontier β* falls from 0.65 at burst size b=1 to 0.5 at b=2, 0.3 at b=4, and at b=8 no β in the tested range is sustainable. Conversely, diversifying the same total domain economy across P=8 independent providers (where each provider's pool can be emptied by a single takedown but providers fail independently) moves the frontier past β=1, and simulated P-provider availability matches the closed form A_P = 1 - q^P geometrically (Proposition 4, Figure 5d).

§8.7, §8.8, Proposition 4, Figure 5 defense

In April 2024 the GFW began decrypting QUIC Initial packets at scale and blocking connections by domain rather than by IP address, targeting the exact transport layer that modern moving-target circumvention systems rely on for session continuity. Because blocking a registrable domain costs the censor essentially zero collateral (unlike blocking a hyperscaler IP range), the censor's optimal Stackelberg budget split allocates f* = 0.97 of its discovery budget to the domain channel once the defender runs n ≥ 2 endpoints (§8.10, Figure 7). GFWatch measurements show hundreds of thousands of domains persistently blocked.

§1, §3, §6, §8.10, Figure 7 detection

Simulator validation shows a sharp phase transition in (α,T)-availability at the sustainability frontier β* ≤ 1. For a canonical configuration of n=8 endpoints and buffer kmax=8, the interval frontier is β* ≈ 0.65, while the time-average crossing is near β ≈ 0.8. Sweeping rotation speed µ/λa from 1 to >100 does not move the frontier — the availability contour over the (β, µ/λa) plane is entirely vertical (Figure 3). The closed-form availability law (Theorem 1) matches simulation to three significant figures across all tested β (Table 2). A rotation-only defender at beta = 1.5 stays below 0.25 availability even at the largest buffer and rotation speed tested, while a domain-aware defender at beta = 0.6 with the same n, mu and pool exceeds 0.95.

§8.2, §8.5, Figure 2, Figure 3, Table 2 evaluation

Russia's TSPU ("Средства противодействия угрозам") system is deployed inline at individual ISP edges rather than at centralized internet exchange points, producing substantial per-ISP heterogeneity: some providers apply layer-7 SNI/Host filtering while others rely primarily on IP-prefix blocklists, and QUIC/HTTP3 is blocked at several major providers. Rollout timing and enforcement depth vary measurably across autonomous systems, meaning a single "Russia passes/fails" test fixture systematically underestimates blocking coverage.

2024-xue-tspu-russia §4–§5 sni-blockingdpihttp3-quic-blockip-blocking

The June 2025 Iran shutdown—carried out during the Iran-Israel war beginning ~June 19—did not use BGP route withdrawals as in 2019. Instead, authorities applied service-level restrictions at the national border: DNS poisoning of foreign destinations, protocol whitelisting permitting only pre-approved domestic services, and DPI to block circumvention-tool traffic. Iran's international traffic fell roughly 90% while the country's BGP routes remained advertised, making the shutdown invisible to BGP-based monitoring systems. OONI measurement volume, which totalled 121,333 in June 2025, collapsed to under 200 submissions on June 19-20.

2025-iran-shutdown-measurement Executive Summary / §2 dpidns-poisoningport-blockingip-blocking

LetsVPN (快连) announced termination of China mainland operations on April 28, 2026, stating the team had attempted adjustments 'almost every hour' for 20 days before concluding the connectivity problem was unsolvable. A follow-up announcement on May 8 declared 'resumption of global standard operations' but explicitly stated it could not guarantee China mainland availability.

2026-anon-2026-27-vpn §3 (快连 / LetsVPN section) ip-blockingdpi

Russia's Roskomnadzor confirmed in February 2026 that it had blocked 469 VPN services used to bypass censorship. Starting December 2025, Russia began blocking the three most commonly used VPN protocols, and from 2025 onward began imposing penalties for promoting VPN services.

2026-anon-2026-27-vpn §5 (Human Rights Watch section) port-blockingdpiip-blocking

In April 2026, Russia nearly completely blocked Telegram, reducing availability without VPN to 5% during the first ten days; Russia's VPN user base was estimated at no less than 40% of the population. Beginning in mid-April, over 20 major Russian websites and platforms (including Gosuslugi, Ozon, Yandex, Sberbank, VK) began restricting access for VPN users, and Russia introduced a whitelist-based service model permitting only state-approved services under certain network restriction states.

2026-anon-2026-27-vpn §4 (俄罗斯 Telegram / OSW section) ip-blockingdpithrottling

Iran's June 2025 shutdown was enforced using fine-grained, service-level techniques rather than BGP withdrawals or a single 'big switch' event: individual protocols were selectively blocked before and after the 7-day full blackout (June 18–25), with the total preparation and recovery periods each lasting roughly 4–5 days. Cloudflare Radar showed HTTP traffic reaching near-zero by June 18 but partial recovery already on June 21, while the authors' vantage point (AS57497) remained unreachable until June 25, confirming heterogeneous recovery across Iranian networks.

2026-anon-insights-into-iranian §2, §3 dpihttp3-quic-blockthrottling