The modern Domain Name System (DNS) provides not only resolution, but also enables intelligent client routing, e.g. for Content Distribution Networks (CDNs). The adoption of IPv6 presents CDNs the opportunity to utilize different paths when optimizing traffic, and the challenge of appropriately mapping IPv6 DNS queries. This work seeks to discover the associations between Internet DNS client resolver IPv6 address(es) and IPv4 address(es). We design and implement two new techniques, one passive and one active, to gather resolver pairings. The passive technique, deployed in Akamai's production DNS infrastructure, opportunistically discovered 674k (IPv4, IPv6) associated address pairs within a six-month period. We find that 34% of addresses are oneto-one, i.e. appear in no other pair, a fraction that increases to ≈ 50% when aggregating IPv6 addresses into /64 prefixes. The one-to-one associations are suggestive, but not a sufficient condition, of dual-stack DNS recursive resolvers. We further substantiate our inferences via PTR records and software versions, and manual verification of sample pairings by three major Network Operators. Complex associations, where e.g. distributed DNS resolution leads to inferred address groupings that span continents and many autonomous systems exist, a subset of which we explore in more depth using the active probing technique. Among potential uses, Akamai is currently utilizing screened output from the passive technique, in conjunction with prior knowledge of IPv4, to inform IPv6 geolocation within its CDN.
The Membrane Optical Imager Real-time Exploitation (MOIRE) program, being developed by BallAerospace and its partners for the Defense Advanced Research Projects Agency (DARPA), seeks to enable technologies that would make orbital telescopes much lighter, more transportable and more cost-effective. MOIRE intends to design and develop a geosynchronous imager featuring a 10-meter diameter membrane optical element system at a distance 50 meters away from the spacecraft bus, with traceability to a future system with a 20-meter diameter primary optic. The program is preparing for a potential future space-based mission through large-scale, ground-based testing. Full-scale deployment testing of two petal segments combined with quarter-scale testing of a full system demonstrated feasibility of the 10-meter primary diameter design. This paper discusses the design, analysis and testing of the primary optic's structural elements.
a b s t r a c tThe hypervelocity ballistic range G at the Arnold Engineering Development Center (AEDC) is extensively used to conduct kinetic energy lethality tests for the Missile Defense Agency (MDA). Over the years, AEDC has continuously responded to the lethality test and evaluation requirements of Ballistic Missile Defense Systems (BMDS) at hypervelocity intercept conditions. Projectiles launched from two-stage light-gas guns experience acceleration loads that are typically orders of magnitude greater than those of the actual missile defense system. These acceleration loads drive design compromises in the projectiles' geometry and mass-density distribution necessary to survive the launch environment. A ''high-fidelity'' projectile with the proper geometry and mass-density distribution would provide a more representative simulation of the flight vehicle kinetic energy release at impact. Prior to the current upgrades, the range G facility provided the capability to launch large projectiles [8-in. (203-mm) diameter] with weights up to 12 kg at launch velocities up to 4 km/s but at acceleration loads near 40 K g's. Current upgrades provide for the capability to launch large-scale ''higher fidelity'' projectiles at the same high velocities but at half the g loads. In addition, AEDC is developing a new technique for controlling the projectile pitch at the point of impact with a simulated target. These unique capabilities will make it possible to obtain more flight-representative lethality data in a ballistic range. This paper describes the upgraded capabilities now in place and continuing plans for further upgrades.Published by Elsevier Ltd.
The views expressed are those of the author and do not reflect the official policy or position of the Department of Defense or the U.S. Government.The MOIRE optical space system, being designed by Ball Aerospace and its partners for DARPA, is a gossamer structure featuring a 10 meter diameter membrane optical element at a distance 50 meters away from the spacecraft bus. The proposed design has traceability to a system with a 20 meter diameter primary optic. As the critical technology of the program, the membrane has received significant analysis and testing time. This paper discusses several challenges and some of the unique solutions and capabilities that Ball Aerospace and its partners are providing.
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