The A refers to the certification on theâ¦ Airframe structure, to work on the wings, structure of the Frame or assemblies such as air vents for repairs. The P stands for Power Plant, The Certification repair for an Engine of a craft which also includes the hydraulic system.
Protocols. There are a number of VPN protocols in use that secure the transport of data traffic over a public network infrastructure. Each protocol varies slightly in the way that data is kept secure. IP security (IPSec) is used to secure communications over the Internet. IPSec traffic can use either transport mode or tunneling to encrypt data traffic in a VPN.
IPSec Overview. 1  IP Security Protocol Authentication Header (AH) Encapsulating Security Payload (ESP) 2  Data Encryption Standard (DES) 3  Triple DES (3DES) 4  Diffie-Hellman (D-H) 5  Message Digest 5 (MD5) 6  Secure Hash Algorithm-1 (SHA-1) 7  Rivest, Shamir, and Adelman (RSA) Signatures. 8  Internet Key Exchange (IKE) 9  Certificate Authorities (CAs)