NASA's data for digital elevation models (DEM) comes from airborne and space-based sources and are useful for analyzing a majority of Earth's terrain.
NASADEM is a significant improvement over the available three-arcsecond SRTM DEM primarily because it will provide a global DEM and associated products at one-arcsecond spacing.
High-resolution Digital Elevation Models (DEM) for non-polar regions at two-meter spatial resolution are now available through NASA’s Commercial SmallSat Data Acquisition (CSDA) program.
The Terra Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) Global Digital Elevation Model (GDEM) Version 3 (ASTGTM) provides a global digital elevation model (DEM) of land areas on Earth at a spatial resolution of 1 arc second (approximately 30 meter horizontal posting at the equator). The development of the ASTER GDEM data products is a collaborative effort between ...
The first ASTER GDEM was released in 2009, with Version 2 being released in 2011. The ASTER GDEM Version 3 maintains the GeoTIFF format and the same gridding and tile structure as in previous versions, with 30-meter spatial resolution and 1°x1° tiles. Version 3 also features a new global product: the ASTER Water Body Dataset (ASTWBD
516 An overview of 301, 302 and 307 The RFC 7231, the current reference for semantics and content of the HTTP/1.1 protocol, defines the 301 (Moved Permanently) and 302 (Found) status code, that allows the request method to be changed from POST to GET.
41 Mostly 301 vs 302 is important for indexing in search engines, as their crawlers take this into account and transfer PageRank when using 301. See Peter Lee's answer for more details.
I thought maybe you had been scammed by someone. 301 is a huge area code, covering a portion of Maryland. I doubt all numbers from there are scams, but thanks for the warning.