IT Questions and Answers :)

Thursday, March 21, 2019

What does a "Framebuffer" do?

What does a "Framebuffer" do?

  • It allows for smoother frame rates whilst in an active remote session by using a portion of RAM
  • It stores an in-memory bitmap for conversion to a video signal that can be displayed
  • It renders bitmap images in a dot matrix data format, displaying a rectangular grid of pixels
  • It stores and displays a graphical image as a rectangular array of pixel colour values. 

What does a "Framebuffer" do?

EXPLANATION

A framebuffer (frame buffer, or sometimes framestore) is a portion of RAM containing a bitmap that drives a video display.
It is a memory buffer containing a complete frame of data. Modern video cards contain framebuffer circuitry in their cores.

SOURCE

https://en.wikipedia.org/wiki/Framebuffer
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Wednesday, March 20, 2019

What settings in VMware would you use to keep VMs together or separate?

What settings in VMware would you use to keep VMs together or separate?

  • VDS
  • Affinity rules
  • NSX
  • Snapshots 

 
What settings in VMware would you use to keep VMs together or separate?

EXPLANATION


An affinity rule is a setting that establishes a relationship between two or more VMware virtual machines (VMs) and hosts.
Affinity rules and anti-affinity rules tell the vSphere hypervisor platform to keep virtual entities together or separated. The rules, which can be applied as either required or preferred, help reduce traffic across networks and keep the virtual workload balanced on available hosts. If two virtual machines communicate frequently and should share a host, the VMware admin can create a VM-VM affinity rule to keep them together. Conversely, if two resource-hungry VMs would tax a host, an anti-affinity rule will keep those VMs from sharing a host.
Affinity rules and anti-affinity rules can be applied between VMs and hosts as well, and a VM can be subject to VM-VM affinity rules and VM-Host affinity rules at the same time. Affinity and anti-affinity rules in a vSphere environment can conflict with one another. For example, two VMs with an anti-affinity relationship may both be linked to a third VM via an affinity rule, but they cannot share a host. Optional affinity rule violation alarms can alert administrators to these events.

SOURCE

https://searchvmware.techtarget.com/definition/affinity-rules
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Tuesday, March 19, 2019

What default port does HTTP use?

What default port does HTTP use?

  • Port 22
  • Port 8080
  • Port 80
  • Port 21 

What default port does HTTP use?

EXPLANATION

Secure Shell Port 22 
Secure Shell is a cryptographic network protocol for operating network services securely over an unsecured network. The best known example application is for remote login to computer systems by users. 
 
Port 8080
PortTCP/UDP - EMC2 (Legato) Networker or Sun Solcitice Backup (Official) [7937-9936]
TCP - HTTP alternate (http_alt)—commonly used for Web proxy and caching server, or for running a Web server as a non-root user (Official)
TCP - Apache Tomcat (Unofficial)
UDP - FilePhile Master/Relay (Unofficial)
The primary protocol and port used by HTTP is TCP port 80. 
Port 80 is the port number assigned to commonly used internet communication protocol, Hypertext Transfer Protocol (HTTP). It is the port from which a computer sends and receives Web client-based communication and messages from a Web server and is used to send and receive HTML pages or data
Port 21 File Transfer Protocol
The File Transfer Protocol is a standard network protocol used for the transfer of computer files between a client and server on a computer network.
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Friday, March 15, 2019

drwxr-xr-x 3 root root 73728 Dec 26 08:39 /usr/bin/ <=== This directory file on an ext4 filesystem is listed in long format (ls -ld). The value of the fifth field, 73728, reports the size of what?

drwxr-xr-x 3 root root 73728 Dec 26 08:39 /usr/bin/ <=== This directory file on an ext4 filesystem is listed in long format (ls -ld). The value of the fifth field, 73728, reports the size of what?

  • The exact size of the directory file, in bytes.
  • The disk usage, in blocks, of the directory and all of its subdirectories.
  • The size in bytes of the total blocks in use by the directory file. [ (bytes/block) * blocks ]
  • The disk usage, in blocks, of the top level of the directory. 

 
drwxr-xr-x 3 root root 73728 Dec 26 08:39 /usr/bin/ <=== This directory file on an ext4 filesystem is listed in long format (ls -ld). The value of the fifth field, 73728, reports the size of what?

EXPLANATION

A directory file contains a list of names and corresponding inodes. 
A newly created directory file on an ext4 filesystem will have only 2 entries, dot "." and dot dot ".."  
The size of the new directory file will be 4096 bytes.  As additional entries are made to the directory, the reported size will remain at 4096 until additional bytes are required for the next directory entry.  At that point, additional blocks will be allocated to the directory and the reported directory file size will increase.
As directory entries are removed, the blocks already allocated to the directory file do not decrease, but allocated blocks are freed for future use by new entries in the directory.
https://unix.stackexchange.com/questions/234065/why-size-reporting-for-directories-is-different-than-other-files#
https://superuser.com/questions/142893/why-is-the-size-of-a-directory-always-4096-bytes-in-unix/1428...
http://www.linfo.org/directory.html
Note that when the same "ls" command is used on a regular file, the size field will report the actual file size in bytes, which is stored in the inode.  The " -s " option to "ls" will report allocated blocks, in addition to actual file size.

SOURCE

https://superuser.com/questions/142893/why-is-the-size-of-a-directory-always-4096-bytes-in-unix/142895
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Thursday, March 14, 2019

What is the unique identifier for network hardware called?

What is the unique identifier for network hardware called?

  • Gettysburg address
  • MAC address
  • IP address
  • Network address 

 
What is the unique identifier for network hardware called?

EXPLANATION

A media access control (MAC) address is a unique identifier associated with network hardware for communicating on the physical network.
A media access control address of a device is a unique identifier assigned to a network interface controller for communications at the data link layer of a network segment. MAC addresses are used as a network address for most IEEE 802 network technologies, including Ethernet and Wi-Fi. In this context, MAC addresses are used in the medium access control protocol sublayer.
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One of your users can receive mail but can't send any. You notice that the "Type of Outgoing Mail Server" field is blank in the mail application. Which of the following protocols will you most likely enter as a value in this field?

One of your users can receive mail but can't send any. You notice that the "Type of Outgoing Mail Server" field is blank in the mail application. Which of the following protocols will you most likely enter as a value in this field?

  • IMAP
  • POP3
  • NMP
  • SMTP

One of your users can receive mail but can't send any. You notice that the "Type of Outgoing Mail Server" field is blank in the mail application. Which of the following protocols will you most likely enter as a value in this field?

EXPLANATION

 

POP In computing, the Post Office Protocol is an application-layer Internet standard protocol used by e-mail clients to retrieve e-mail from a server in an Internet Protocol network. POP version 3 is the most recent level of development in common use. POP has largely been superseded by the Internet Message Access Protocol.
 
IMAP In computing, the Internet Message Access Protocol is an Internet standard protocol used by email clients to retrieve email messages from a mail server over a TCP/IP connection. IMAP is defined by RFC 3501.
  SMTP is used to send email and is a protocol within the TCP/IP protocol suite. POP3 and IMAP are email retrieval protocols, not protocols for sending email.

 
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Wednesday, March 13, 2019

Linux and Unix systems typically track 3 timestamps in file inodes: atime, ctime, and mtime. The "a" in atime means access. The "m" in mtime means modify. What does the "c" in ctime mean?

Linux and Unix systems typically track 3 timestamps in file inodes: atime, ctime, and mtime. The "a" in atime means access. The "m" in mtime means modify. What does the "c" in ctime mean?

  • cache
  • create
  •  change
  • copy-on-write 

 
Linux and Unix systems typically track 3 timestamps in file inodes: atime, ctime, and mtime. The "a" in atime means access. The "m" in mtime means modify. What does the "c" in ctime mean?

EXPLANATION

"c" in ctime means change.  Specifically, a change to the inode's status, eg, permissions, ownership, link count, file size, etc.
http://man7.org/linux/man-pages/man7/inode.7.html
"Last status change timestamp (ctime) stat.st_ctime; statx.stx_ctime"

http://www.linux-mag.com/id/8658/
"Timestamps telling when the inode itself was last change (ctime, changing time), the file content was last modified (mtime or modification time), and when the file was last accessed (atime or access time)"

SOURCE

http://man7.org/linux/man-pages/man7/inode.7.html
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Tuesday, March 12, 2019

When it comes to SNMP technology, what is the range of the "Counter32" parameter?

When it comes to SNMP technology, what is the range of the "Counter32" parameter?

  • 0 to 4294967295
  • 0 to 1099511627776
  • 32 to 272
  • -100 to 100 

 
When it comes to SNMP technology, what is the range of the "Counter32" parameter?

EXPLANATION

The Counter32 class allows all the functionality of unsigned integers but is recognized as a distinct SMI type, which specifies a value that represents a count.
The range is 0 to 4294967295

https://www.webnms.com/snmp/help/snmpapi/snmpv3/using_mibs_in_applns/countr32.html

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Monday, March 11, 2019

What is the fastest back-end database for OpenLDAP ?

What is the fastest back-end database for OpenLDAP ?

  • hdb
  • sql
  • mdb
  • bdb 

 

EXPLANATION

  • A file with the MDB file extension is a Microsoft Access Database file that literally stands for Microsoft Database. ...
  • MDB files contain database queries, tables, and more that can be used to link to and store data from other files, like XML and HTML, and applications, like Excel and SharePoint.

 

http://www.openldap.org/pub/hyc/mdm-paper.pdf

SOURCE

http://www.openldap.org/pub/hyc/mdm-paper.pdf
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Which of these is NOT a use case of Microsoft Azure Stack?

Which of these is NOT a use case of Microsoft Azure Stack?

  • Update and extend legacy applications with modern Azure services on-premise
  • Address latency and connectivity requirements for edge and disconnected solutions
  • Develop applications and deploy in Azure or on-premises to meet regulatory and policy requirements
  • The next-gen Hyper-V platform for you to migrate your current workloads on your existing hardware 

Which of these is NOT a use case of Microsoft Azure Stack?

EXPLANATION

If you answered "next-gen Hyper-V platform for you to migrate..." then yes you're correct - that is NOT the intended use case of Microsoft Azure Stack.  Microsoft Windows Server Software Defined (WSSD)
is a better solution to implement virtualization in scale within your datacenter.   Azure Stack's three primary use cases can be found at the link provided to learn more.

SOURCE

https://azure.microsoft.com/en-us/overview/azure-stack/
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Friday, March 8, 2019

CPUs have a NX flag/bit to segregate areas of memory for process instruction or data. What does NX stand for?

CPUs have a NX flag/bit to segregate areas of memory for process instruction or data. What does NX stand for?

  • NineX
  • Non-Existent
  • No-Execute
  • Near-Exact 
CPUs have a NX flag/bit to segregate areas of memory for process instruction or data. What does NX stand for?

EXPLANATION


The NX bit (no-execute) is a technology used in CPUs to segregate areas of memory for use by either storage of processor instructions (code) or for storage of data, a feature normally only found in Harvard architecture processors. However, the NX bit is being increasingly used in conventional von Neumann architecture processors, for security reasons.
An operating system with support for the NX bit may mark certain areas of memory as non-executable. The processor will then refuse to execute any code residing in these areas of memory. The general technique, known as executable space protection, is used to prevent certain types of malicious software from taking over computers by inserting their code into another program's data storage area and running their own code from within this section; one class of such attacks is known as the buffer overflow attack.
Intel markets the feature as the XD bit (execute disable). Advanced Micro Devices (AMD) uses the marketing term Enhanced Virus Protection (EVP). The ARM architecture refers to the feature, which was introduced in ARMv6, as XN (execute never).[1] The term NX bit itself is sometimes used to describe similar technologies in other processors.

SOURCE

https://en.wikipedia.org/wiki/NX_bit
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You are getting a DNS lookup error when trying to access any webpage that your local DNS server has no record for, what should you check?

You are getting a DNS lookup error when trying to access any webpage that your local DNS server has no record for, what should you check?

  • The Forwarders on your DNS server
  • The Reverse Lookup Zones on your DNS server
  • The CNAME records on your DNS server for your host
  • The Forward Lookup Zones on your DNS 

 
You are getting a DNS lookup error when trying to access any webpage that your local DNS server has no record for, what should you check?

EXPLANATION

In Domain Name System (DNS) terms, a DNS forwarder is a DNS server that is used to forward DNS queries for external DNS names to DNS servers outside that network. It does it to DNS queries that it cannot resolve locally, meaning DNS queries
that it has no personal knowledge of. By using DNS forwarders you can improve the efficiency of name resolution for the computers in your network that query for DNS names outside your network (such as names on the Internet).

SOURCE

https://www.petri.com/best-practices-for-dns-forwarding
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Thursday, March 7, 2019

What type of attack has a program running on your server that bypasses authorization?

What type of attack has a program running on your server that bypasses authorization?

  • Backdoor
  • DDoS
  • Phishing
  • DoS 

 
What type of attack has a program running on your server that bypasses authorization?

EXPLANATION

When a program running on a server bypasses authorization, it is obvious that a back door attack is in progress.
Key Takeaway: In a back door attack, a program or service is placed on a server to bypass normal security procedures. A back door is a program that is designed to hide itself inside a target host. It allows the installing user access to the system at a later time without using normal authorization or vulnerability exploitation.

http://www.hbs.net/blog/december-2016/bypassing-security-controls-cyber-crime
https://www.incapsula.com/web-application-security/backdoor-shell-attack.html
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Wednesday, March 6, 2019

Which of the following is an IPSLA option?

Which of the following is an IPSLA option?

  • Object-tracking
  • Reachability
  • Icmp-probing
  • IGMP-Snooping 

 
Which of the following is an IPSLA option?

EXPLANATION

The correct option is reachability.  This option permits the cisco device to track connectivity to an object, and change routes
accordingly based upon failure of the primary path.

SOURCE

http://www.firewall.cx/cisco-technical-knowledgebase/cisco-routers/813-cisco-router-ipsla-basic.html
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In T-SQL, which of the following is NOT a requirement to define a table expression?

In T-SQL, which of the following is NOT a requirement to define a table expression?

  • All columns must have a name
  • Column names must be unique
  • Must be preceded by WITH
  • Cannot use ORDER BY to guarantee presentation order 

 
In T-SQL, which of the following is NOT a requirement to define a table expression?

 

EXPLANATION

Table expressions in SQL Server are named query expressions that represent a valid relational table. SQL Server supports four types of table expressions: Common Table Expressions (CTEs), Derived Tables, Views and In-line Table-Valued Functions. Only a CTE definition needs to be preceded by WITH.

T-SQL allows the ORDER BY clause in conjunction with TOP, OFFSET or FOR XML for processing purposes, but this does not guarantee presentation order in an outer query that references the table expression.


SOURCE

https://www.microsoftpressstore.com/articles/article.aspx?p=2233323
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What's the basic unit of virtualization that contains an OS, its apps, and resources?

What's the basic unit of virtualization that contains an OS, its apps, and resources?

  • Virtual app
  • Virtual machine
  • Virtual reality
  • Virtual OS 

 
What's the basic unit of virtualization that contains an OS, its apps, and resources?

EXPLANATION

A virtual machine (VM) is a type of container you can assign resources to, like processing cores, memory, and storage. You can install an operating system in a VM and the OS will behave as if it's actually running on a physical computer.

Virtual machines

Another form of virtual machine is one that allows us to run multiple operating systems concurrently, sharing access to the physical machine resources. With this for of virtual machine, we can partition one computer to act like several computers, each with its own operating system (and IP address on the network). We can also migrate an entire OS (along with all of its applications) from one machine to another.
To understand how this form of virtualization works, we need to consider what an operating system does. Basically, it provides a set of interfaces (system calls) that applications use to access system resources (file system, network, semaphores, etc.). The operating system is just a program. It spends its time doing table look-ups, copying blocks of data, formatting network packet headers, and other mundane tasks. Every once in a while, however, it needs to access system hardware: to configure the memory management unit, set a timer, set the task register, and perform certain types of input and output. These instructions are called privileged instructions, in contrast to all the other instructions on the processor, which are unprivileged. To execute them, the operating system kernel runs in privileged, or supervisor mode, while regular processes do not. If a regular application attemts to execute a privileged instruction, it will generate a trap on many architectures.

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Friday, March 1, 2019

Which statement is not true about SQL Injection?

Which statement is not true about SQL Injection?

  • Boosts database performace.
  • The placement of malicious code in SQL statements
  • A code injection technique that might destroy your database.
  • One of the most common web hacking techniques. 

 
Which statement is not true about SQL Injection?

EXPLANATION

SQL Injection does not boost database performance.

SQL injection is the placement of malicious code in SQL
statements, via web page input. SQL in Web Pages SQL injection usually occurs when you ask a user for input, like their username/userid, and instead of a name/id, the user gives you an SQL statement that you will unknowingly run on your database.

SOURCE

https://www.w3schools.com/sql/sql_injection.asp
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What port is recommended for secure SMTP communications between client and mailserver.

What port is recommended for secure SMTP communications between client and mailserver.

  • 587
  • 965
  • 465
  • 25 

 
What port is recommended for secure SMTP communications between client and mailserver.

EXPLANATION

Port 465 was never recognized by the IETF (Internet Engineering Task Force), as an official port for SMTP and has been assigned to another service.
Port 25 can be used but alot of ISP's block this due to the prevalence of unsecured mail servers on this port and the spam sending capabilities this exposes. Port 965 is your POP3 (receive) port, so while it is the correct POP3 port it shouldn't be used for SMTP (send).

SOURCE

https://www.jscape.com/blog/smtp-ports
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Thursday, February 28, 2019

In Windows, this is a snapshot of your computer's settings at a specific time.

In Windows, this is a snapshot of your computer's settings at a specific time.

  • Ghost image
  • System protection
  • Restore point
  • Rollback marker 

In Windows, this is a snapshot of your computer's settings at a specific time.

EXPLANATION

In Windows, a restore point is a backup copy of all your settings at a particular time. If some disaster occurs, you can restore your system to the most recent restore point. 

System Restore is a feature in Microsoft Windows that allows the user to revert their computer's state to that of a previous point in time, which can be used to recover from system malfunctions or other problems. First included in Windows ME, it has been included in all following desktop versions of Windows released since, excluding the Windows Server. In Windows 10, System Restore is turned off by default and must be enabled by users in order to function.Wikipedia
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On a UNIX or MacOS system, what is the term for what, on the Windows OS, is commonly known as the Blue Screen of Death (BSOD)?

On a UNIX or MacOS system, what is the term for what, on the Windows OS, is commonly known as the Blue Screen of Death (BSOD)?

  • Integrity Check Failure
  • Kernel Lock
  • Kernel Panic
  • Buffer Overflow 

 
On a UNIX or MacOS system, what is the term for what, on the Windows OS, is commonly known as the Blue Screen of Death (BSOD)?

EXPLANATION

Since the kernel handles the most basic functions of a computer, if it crashes it can take down the entire computer. This undesirable event is called a "kernel panic"
on m=MacOS and Unix systems. It is similar to the blue screen of death in Windows.

SOURCE

https://techterms.com/definition/kernel
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Monday, February 25, 2019

The hexadecimal 7F3E converted to binary is?

The hexadecimal 7F3E converted to binary is?

  • 0111 1111 1100 1110
  • 1000 1111 0011 1110
  • 0111 1111 0011 1101
  • 0111 1111 0011 1110 
 
The hexadecimal 7F3E converted to binary is?

EXPLANATION

7 = 0111
F = 1111
3 = 0011
E = 1110
 
DecimalBinaryHexadecimal
000000
100011
200102
300113
401004
501015
601106
701117
810008
910019
101010A
111011B
121100C
131101D
141110E
151111F

160001 000010
170001 000111
180001 001012
190001 001113
200001 010014
210001 010115
220001 011016
230001 011117
240001 100018
250001 100119
260001 10101A
270001 10111B
280001 11001C
290001 11011D
300001 11101E
310001 11111F
320010 000020
330010 000121
340010 001022
350010 001123
360010 010024
370010 010125
380010 011026
390010 011127
400010 100028
410010 100129
420010 10102A
430010 10112B
440010 11002C
450010 11012D
460010 11102E
470010 11112F
480011 000030
490011 000131
500011 001032
510011 001133
520011 010034
530011 010135
540011 011036
550011 011137
560011 100038
570011 100139
580011 10103A
590011 10113B
600011 11003C
610011 11013D
620011 11103E
630011 11113F
640100 000040
650100 000141
660100 001042
670100 001143
680100 010044
690100 010145
700100 011046
710100 011147
720100 100048
730100 100149
740100 10104A
750100 10114B
760100 11004C
770100 11014D
780100 11104E
790100 11114F
800101 000050
810101 000151
820101 001052
830101 001153
840101 010054
850101 010155
860101 011056
870101 011157
880101 100058
890101 100159
900101 10105A
910101 10115B
920101 11005C
930101 11015D
940101 11105E
950101 11115F
960110 000060
970110 000161
980110 001062
990110 001163
1000110 010064
1010110 010165
1020110 011066
1030110 011167
1040110 100068
1050110 100169
1060110 10106A
1070110 10116B
1080110 11006C
1090110 11016D
1100110 11106E
1110110 11116F
1120111 000070
1130111 000171
1140111 001072
1150111 001173
1160111 010074
1170111 010175
1180111 011076
1190111 011177
1200111 100078
1210111 100179
1220111 10107A
1230111 10117B
1240111 11007C
1250111 11017D
1260111 11107E
1270111 11117F
1281000 000080
1291000 000181
1301000 001082
1311000 001183
1321000 010084
1331000 010185
1341000 011086
1351000 011187
1361000 100088
1371000 100189
1381000 10108A
1391000 10118B
1401000 11008C
1411000 11018D
1421000 11108E
1431000 11118F
1441001 000090
1451001 000191
1461001 001092
1471001 001193
1481001 010094
1491001 010195
1501001 011096
1511001 011197
1521001 100098
1531001 100199
1541001 10109A
1551001 10119B
1561001 11009C
1571001 11019D
1581001 11109E
1591001 11119F
1601010 0000A0
1611010 0001A1
1621010 0010A2
1631010 0011A3
1641010 0100A4
1651010 0101A5
1661010 0110A6
1671010 0111A7
1681010 1000A8
1691010 1001A9
1701010 1010AA
1711010 1011AB
1721010 1100AC
1731010 1101AD
1741010 1110AE
1751010 1111AF
1761011 0000B0
1771011 0001B1
1781011 0010B2
1791011 0011B3
1801011 0100B4
1811011 0101B5
1821011 0110B6
1831011 0111B7
1841011 1000B8
1851011 1001B9
1861011 1010BA
1871011 1011BB
1881011 1100BC
1891011 1101BD
1901011 1110BE
1911011 1111BF
1921100 0000C0
1931100 0001C1
1941100 0010C2
1951100 0011C3
1961100 0100C4
1971100 0101C5
1981100 0110C6
1991100 0111C7
2001100 1000C8
2011100 1001C9
2021100 1010CA
2031100 1011CB
2041100 1100CC
2051100 1101CD
2061100 1110CE
2071100 1111CF
2081101 0000D0
2091101 0001D1
2101101 0010D2
2111101 0011D3
2121101 0100D4
2131101 0101D5
2141101 0110D6
2151101 0111D7
2161101 1000D8
2171101 1001D9
2181101 1010DA
2191101 1011DB
2201101 1100DC
2211101 1101DD
2221101 1110DE
2231101 1111DF
2241110 0000E0
2251110 0001E1
2261110 0010E2
2271110 0011E3
2281110 0100E4
2291110 0101E5
2301110 0110E6
2311110 0111E7
2321110 1000E8
2331110 1001E9
2341110 1010EA
2351110 1011EB
2361110 1100EC
2371110 1101ED
2381110 1110EE
2391110 1111EF
2401111 0000F0
2411111 0001F1
2421111 0010F2
2431111 0011F3
2441111 0100F4
2451111 0101F5
2461111 0110F6
2471111 0111F7
2481111 1000F8
2491111 1001F9
2501111 1010FA
2511111 1011FB
2521111 1100FC
2531111 1101FD
2541111 1110FE
2551111 1111FF
 
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