NSA Computer Network Test Questions with complete Solutions Graded A+
What are the 2 keys to decimal/hex/octal/binary conversions? - Answers 1. Binary is the intermediary
2. BE CAREFUL
What is endianness? - Answers The order or sequence of bytes of a word of digital data in computer
memory
What is big endian? - Answers The most significant byte is stored at the smallest memory address and
the least significant byte is stored at the largest memory address
What is little endian? - Answers The most significant byte is stored at the largest memory address and
the least significant byte is stored at the smallest memory address
With regards to endianness, what is "network order?" - Answers Network order refers to data being sent
across a medium in big endian (most significant byte first) in the Internet Protocol
What is the endianness of most processor architectures, including Intel x86, AMD x86-64, ARM, and
RISK-V? - Answers Little endian
In what two situations is paying attention to endianness important? - Answers 1. When sending data
between two different computers. The communication protocol must ensure that even if the two
computers' endianness differs, the data isn't corrupted. IP does this by defaulting to network order.
2. When investigating memory dumps. You must understand the endianness of the computer whom the
memory dump comes from to properly be able to analyze the dump.
4 part memory hierarchy - Answers 1. Registers
2. Caches
3. Main memory
4. Storage
How many bytes are in a word? - Answers 2 bytes
How many bytes are in a single ASCII character? - Answers 1 byte
How many bytes are in a single UTF-8 character? - Answers 1 to 4 bytes (variable)
What are the 5 segments of a process's memory? - Answers From low to high addresses:
1. Text segment (code / executable instructions)
2. Initialized data segment
,3. Uninitialized data segment
4. Heap segment (dynamic memory allocations, grows toward high addresses)
5. Stack segment (function arguments, local variables, grows toward low addresses)
What is a *solid state drive*? - Answers An SSD is a form of memory that uses integrated circuits for
persistent memory (flash memory)
What is a *hard disk drive*? - Answers An HDD is a form of memory that uses magnetic properties to
store and retrieve digital data on spinning disks
What is user space? - Answers The section of memory in which normal user processes run. Processes
running in this space only have access to a limited part of this space (the process's own space and any
shared memory sections). Process in this space can only access kernel space through controlled system
calls.
What is kernel space? - Answers The section of memory in which kernel processes run. Processes
running in this space have access to all memory spaces, user and kernel. Significantly higher privilege
than user space.
Name the seven layers of the *OSI model* - Answers 1: Physical
2: Data Link
3: Network
4: Transport
5: Session
6: Presentation
7: Application
Name the four layers of the *TCP/IP model* - Answers 1: Link
2: Internet
3: Transport
4: Application
What is encapsulation? - Answers As data travels down the TCP/IP stack, the packet of the higher layer
becomes the payload of the packet of the next lower layer.
As data travels up the TCP/IP stack, the payload of each packet is extracted at each layer of the stack.
, What is the primary concern of the *Physical layer* of the OSI model? - Answers The transmission of
raw bits
What are the primary 3 concerns of the *Data Link layer* of the OSI model? - Answers 1. Grouping raw
bits from the Physical layer in to frames
2. Detect and possibly correct errors from the Physical layer (checksum)
3. The transmission of data frames between nodes on a network
What are the 3 primary concerns of the *Network layer* of the OSI model? - Answers 1. Provide an
addressing scheme
2. The forwarding/routing of data packets between networks
3. Frame fragmentation with MTU field
What is the primary concern of the *Transport layer* of the OSI model? - Answers Provide host-to-host
communication services for applications (such as connection-oriented communication, connectionless
communication, reliability, flow control, and multiplexing) through the transmission of data segments
What are the four primary concerns of the *Session layer* of the OSI model? - Answers Provides a
mechanism for:
(1) Delimiting data flow
(2) Synchronizing data flow
(3) Maintaining state
(4) Checkpoint/recovery scheme
What are the four primary concerns of the *Presentation layer* of the OSI model? - Answers How data
is formatted in a given session, including:
(1) Compression
(2) Encryption
(3) Byte-ordering
(4) Encoding
What is the primary concern of the *Application layer* of the OSI model? - Answers Provide services
that allow end users to easily interface across the network
At what level of the OSI model does a *web application firewall* operate? - Answers The Application
layer
What are the 2 keys to decimal/hex/octal/binary conversions? - Answers 1. Binary is the intermediary
2. BE CAREFUL
What is endianness? - Answers The order or sequence of bytes of a word of digital data in computer
memory
What is big endian? - Answers The most significant byte is stored at the smallest memory address and
the least significant byte is stored at the largest memory address
What is little endian? - Answers The most significant byte is stored at the largest memory address and
the least significant byte is stored at the smallest memory address
With regards to endianness, what is "network order?" - Answers Network order refers to data being sent
across a medium in big endian (most significant byte first) in the Internet Protocol
What is the endianness of most processor architectures, including Intel x86, AMD x86-64, ARM, and
RISK-V? - Answers Little endian
In what two situations is paying attention to endianness important? - Answers 1. When sending data
between two different computers. The communication protocol must ensure that even if the two
computers' endianness differs, the data isn't corrupted. IP does this by defaulting to network order.
2. When investigating memory dumps. You must understand the endianness of the computer whom the
memory dump comes from to properly be able to analyze the dump.
4 part memory hierarchy - Answers 1. Registers
2. Caches
3. Main memory
4. Storage
How many bytes are in a word? - Answers 2 bytes
How many bytes are in a single ASCII character? - Answers 1 byte
How many bytes are in a single UTF-8 character? - Answers 1 to 4 bytes (variable)
What are the 5 segments of a process's memory? - Answers From low to high addresses:
1. Text segment (code / executable instructions)
2. Initialized data segment
,3. Uninitialized data segment
4. Heap segment (dynamic memory allocations, grows toward high addresses)
5. Stack segment (function arguments, local variables, grows toward low addresses)
What is a *solid state drive*? - Answers An SSD is a form of memory that uses integrated circuits for
persistent memory (flash memory)
What is a *hard disk drive*? - Answers An HDD is a form of memory that uses magnetic properties to
store and retrieve digital data on spinning disks
What is user space? - Answers The section of memory in which normal user processes run. Processes
running in this space only have access to a limited part of this space (the process's own space and any
shared memory sections). Process in this space can only access kernel space through controlled system
calls.
What is kernel space? - Answers The section of memory in which kernel processes run. Processes
running in this space have access to all memory spaces, user and kernel. Significantly higher privilege
than user space.
Name the seven layers of the *OSI model* - Answers 1: Physical
2: Data Link
3: Network
4: Transport
5: Session
6: Presentation
7: Application
Name the four layers of the *TCP/IP model* - Answers 1: Link
2: Internet
3: Transport
4: Application
What is encapsulation? - Answers As data travels down the TCP/IP stack, the packet of the higher layer
becomes the payload of the packet of the next lower layer.
As data travels up the TCP/IP stack, the payload of each packet is extracted at each layer of the stack.
, What is the primary concern of the *Physical layer* of the OSI model? - Answers The transmission of
raw bits
What are the primary 3 concerns of the *Data Link layer* of the OSI model? - Answers 1. Grouping raw
bits from the Physical layer in to frames
2. Detect and possibly correct errors from the Physical layer (checksum)
3. The transmission of data frames between nodes on a network
What are the 3 primary concerns of the *Network layer* of the OSI model? - Answers 1. Provide an
addressing scheme
2. The forwarding/routing of data packets between networks
3. Frame fragmentation with MTU field
What is the primary concern of the *Transport layer* of the OSI model? - Answers Provide host-to-host
communication services for applications (such as connection-oriented communication, connectionless
communication, reliability, flow control, and multiplexing) through the transmission of data segments
What are the four primary concerns of the *Session layer* of the OSI model? - Answers Provides a
mechanism for:
(1) Delimiting data flow
(2) Synchronizing data flow
(3) Maintaining state
(4) Checkpoint/recovery scheme
What are the four primary concerns of the *Presentation layer* of the OSI model? - Answers How data
is formatted in a given session, including:
(1) Compression
(2) Encryption
(3) Byte-ordering
(4) Encoding
What is the primary concern of the *Application layer* of the OSI model? - Answers Provide services
that allow end users to easily interface across the network
At what level of the OSI model does a *web application firewall* operate? - Answers The Application
layer
