In Vsphere 6.0, what is the primary difference between a vSS switch and a vDS switch?

In Vsphere 6.0, what is the primary difference between a vSS switch and a vDS switch?

• vSS supports host only networking. vDS switches share network resources across multiple hosts
• vSS supports only 2 hosts. vDS must be used for 3 or more hosts.
• vSS switches and vDS switches are essentially the same
• vSS switches are standard and vDS are virtual 

 

EXPLANATION

vSS (standard switch) works within one ESXi host only. vDS enables more features and allows the switches to be used by multiple hosts.
Searchvmware.techtarget.com
Vmware terminology

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Which of these is NOT a valid ping command

Which of these is NOT a valid ping command

• ping 0x08080808
• ping 8.8.8.8 google.com
• ping 127.1
• ping 01002004010 

 

EXPLANATION

PING 127.1 is a valid command because it is a short form of 127.0.0.1, same as IPv6 addresses, IPv4 addresses can be shortened by removing leading zeroes. See page 4 of RFC3513
PING 01002004010 is a valid ping command as it is the octal number form of 8.8.8.8.
PING 0x08080808 is a valid ping command as it is the hex number form of 8.8.8.8

PING 8.8.8.8 google.com is NOT valid because of multiple destinations referenced.
See the ping man page.
These conversions may not be useful for day to day IT pros, but in security, it is a huge threat as skilled attackers can use this technique to conceal their IPs from Web Application Firewalls (WAF) since these firewalls only have rules created for IP addresses.
This tool converts IP to different number formats (it's not limited to IP addresses, other bidirectional formats are available)
P.S This question stemmed from this tweet

SOURCE

https://tools.ietf.org/html/rfc3513

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What CIDR would be used to restrict a network to 100 hosts?

What CIDR would be used to restrict a network to 100 hosts?

• /26
• /12
• /25
• /30 

EXPLANATION

---

	Addresses	Hosts	Netmask	Amount of a Class C
/30	4	2	255.255.255.252	1/64
/29	8	6	255.255.255.248	1/32
/28	16	14	255.255.255.240	1/16
/27	32	30	255.255.255.224	1/8
/26	64	62	255.255.255.192	1/4
/25	128	126	255.255.255.128	1/2
/24	256	254	255.255.255.0	1
/23	512	510	255.255.254.0	2
/22	1024	1022	255.255.252.0	4
/21	2048	2046	255.255.248.0	8
/20	4096	4094	255.255.240.0	16
/19	8192	8190	255.255.224.0	32
/18	16384	16382	255.255.192.0	64
/17	32768	32766	255.255.128.0	128
/16	65536	65534	255.255.0.0	256

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What does CTRL-ALT-DEL actually do, when at the BIOS screen?

What does CTRL-ALT-DEL actually do, when at the BIOS screen?

• Sends an interrupt 999 to the CPU
• Sends an interrupt 0 to the CPU
• Sends an interrupt 443 to the CPU
• Sends an interrupt 9 to the CPU 

EXPLANATION

If Ctrl+Alt+Del is executed before Windows is to a point where it can intercept the command, BIOS will simply restart the computer. Ctrl+Alt+Del might also restart the computer while in Windows if Windows is locked up in a certain way. For example, using Ctrl+Alt+Del during the Power On Self Test reboots the computer.

In Windows 3.x and 9x, if Ctrl+Alt+Del is quickly pressed twice in a row, the system will immediately start a reboot without safely shutting down any open programs or processes. The page cache is flushed and any volumes are safely unmounted, but there isn't an opportunity to cleanly shut down running programs or save any work.

 

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A PC connects to two working networks using SOHO routers and different subnets. One of the routers doesn't connect to the Internet, but the other does. You lose access to the Internet when the isolated network is connected. What the likely cause?

A PC connects to two working networks using SOHO routers and different subnets. One of the routers doesn't connect to the Internet, but the other does. You lose access to the Internet when the isolated network is connected. What the likely cause?

• The test network route metric is lower.
• Your Internet goes out at the same time.
• Network issues on the Internet side.
• A system can't be on two separate subnets at once. 

EXPLANATION

 Two subnets on a single VLAN isn't practical.

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