You Must know this no matter which test you take

Weather it is Security+, CEH, ECSA, or most other security certifications, there are some items of common knowledge to all of these exams.

THe Frame

​A data packet on an Ethernet link is called an Ethernet packet, which transports an Ethernet frame as its payload.[1]

An Ethernet frame is preceded by a preamble and start frame delimiter (SFD), which are both part of the Ethernet packet at the physical layer. Each Ethernet frame starts with an Ethernet header, which contains destination and source MAC addresses as its first two fields. The middle section of the frame is payload data including any headers for other protocols (for example, Internet Protocol) carried in the frame. The frame ends with a frame check sequence (FCS), which is a 32-bit cyclic redundancy check used to detect any in-transit corruption of data. - Wikipedia

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Asymmetric   vs   Symmetric algorithms

Asymmetric

• X25519 key exchange
• Elliptic curve cryptography
• RSA
• Diffie-Hellman key exchange
• DSA
• Key Serialization
• Asymmetric Utilities

Symmetric

• ​​DES
  

The Data Encryption Standard or DES was, and probably still is, one of the more well-known algorithms of the modern cryptographic era.

• AES

The Advanced Encryption Standard or AES was established by the National Institute of Standards and Technology (NIST) in 2001.

• MARS

After DES was found to be weak, NIST ran an open call process known as the Advanced Encryption Standard Process from 1997 to 2000 to find a new and improved block cipher.

• IDEA

The International Data Encryption Algorithm (IDEA), originally called the Improved Proposed Encryption Standard (IPES), was designed by James Massey of ETH Zurich under a research contract with the Hasler Foundation, now Ascom Tech AG ,and was first discussed in 1991. 

• RC 2

Rivet’s cipher, Ron’s code or, more commonly, RC algorithms were invented by Ron Rivest. 

• RC4

RC4 was designed by Ron Rivest in 1987 initially as a trade secret until it was posted in the Cypherpunks mailing list in 1994.

• RC5

Ron Rivest designed RC5 in 1994 to be variable on all fronts. Block sizes can vary from 32, 64 or 128 bits and key sizes from 0-2040 bits and rounds from 0-255.

• RC6

RC6 was derived from RC5 by Ron Rivest and colleagues. It was designed to meet the requirements of the Advanced Encryption Standard competition and managed to become one of the five finalists.

• Blowfish

Blowfish is a symmetric block cipher built by Bruce Schneier as a replacement to DES and IDEA. 

• Twofish

Twofish is Blowfish’s successor published in 1998. With a block size of 128-bits, key sizes up to 256-bits and 16 rounds, it became one of the five finalists of the Advanced Encryption Standard competition but was not selected for standardization. 

• Threefish

Threefish worked on 256-bit, 512-bit and 1024-bit blocks with the same key sizes as the block and up to 80 rounds. Threefish was created in 2008 as part of the Skein Hash Function, one of five finalists of the NIST’s SHA-3 hash function competition. 

• Serpent

Serpent was also entered into the Advanced Encryption Standard competition and was actually ranked second to Rijndael (now known as AES). Serpent was designed in 1998 by Ross Anderson, Eli Buham and Lars Knudsen.