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. 

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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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 

 

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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What default port does HTTP use?

What default port does HTTP use?

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

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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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. 

 

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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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 

 

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

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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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 

 

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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