What internet protocol is used to stream videos and audio on the internet?
- UDP
- IPX
- IP
- TCP
What internet protocol is used to stream videos and audio on the internet?
Friday, August 30, 2019
Wednesday, August 28, 2019
Simple mail transfer protocol (SMTP) commonly uses __________ as the transport layer protocol for electronic mail transfer.
Simple mail transfer protocol (SMTP) commonly uses __________ as the transport layer protocol for electronic mail transfer.
- DCCP
- TCP
- UDP
- SCTP
EXPLANATION
The Simple Mail Transfer Protocol (SMTP) is a communication protocol for electronic mail transmission. As an Internet standard, SMTP was first defined in 1982 by RFC 821, and updated in 2008 by RFC 5321 to Extended SMTP additions, which is the protocol variety in widespread use today. Mail servers and other message transfer agents use SMTP to send and receive mail messages. Proprietary systems such as Microsoft Exchange and IBM Notes and webmail systems such as Outlook.com, Gmail and Yahoo! Mail may use non-standard protocols internally, but all use SMTP when sending to or receiving email from outside their own systems.SMTP servers commonly use the Transmission Control Protocol on port number 25.
User-level email clients typically use SMTP only for sending messages to a mail server for relaying, typically submit outgoing email to the mail server on port 587 or 465 as per RFC 8314. For retrieving messages, IMAP and POP3 are standard, but proprietary servers also often implement proprietary protocols, e.g., Exchange ActiveSync.
If you're going to secure your Exchange server, the best place for the front-end server is...
If you're going to secure your Exchange server, the best place for the front-end server is...
- At a hosted location
- Outside the firewall
- The internal network
- The internal network with ISA in the perimeter
EXPLANATION
The generally accepted way of implementing a front end / backend configuration involves placing an ISA Server in front of the front end server.The idea behind this configuration is that remote clients never interact directly with the front end server. Instead, the ISA Server is provided with a copy of the front end server's certificate, which allows it to impersonate the front end Exchange Server. Remote clients never actually communicate with the front end Exchange Server. Instead, remote clients communicate with the ISA server. The ISA server acts as a proxy server and forwards HTTP requests to the front end Exchange Server.
Part of the ISA server's job is to act as an application firewall for Exchange Server. What this means is that ISA server knows what types of communications are considered normal for an Exchange Server environment. It is therefore able to filter out abnormal and potentially malicious packets.
The merits of using an ISA server are sometimes debated though. The reason why this is a debated topic is that ISA Server is a software based firewall sitting on top of a Windows operating system. Some people feel that it is therefore vulnerable to the same types of attacks that any other Windows server would be.
My take on this issue is that ISA Server should be considered an essential part of a front end / back end configuration. ISA Server is not a generic firewall. It was developed by Microsoft with Exchange in mind. It contains lots of Exchange specific filtering rules that will help to keep your Exchange Server secure. At the same time though, I believe that the fact that ISA Server rides on top of a Windows operating system does pose a security threat. In my opinion, the best way to counter this threat is to place a hardware-based firewall at your network's perimeter and then have your hardware firewall forward the inbound HTTP requests to an ISA Server located behind it.
Which of the following methods is not a secure way to connect clients to Exchange?
Which of the following methods is not a secure way to connect clients to Exchange?
- Outlook using MAPI/RPC
- Outlook Web Access over HTTPS
- Outlook using RPC over HTTPS
- Outlook using IMAP4 with SSL
EXPLANATION
The point they're making is that "traditional RPC" sometimes uses unusual low-level network protocols that often get blocked by corporate firewalls. Because SOAP uses HTTP, it's traffic is "indistinguishable" from normal web page views, and so is not caught out by these firewalls. Not too sure about the security point, I think they're probably implying that HTTP can easily be secured over HTTPS and that proprietary RPC protocols often don't. Of course, this is protocol dependant, not all RPC protocols will be insecure, and many of them can be tunnelled over HTTPS.
RPC over HTTP, also known as Outlook Anywhere, is a legacy method of connectivity and transport between Outlook for Windows and Exchange. In May 2014, Microsoft introduced MAPI over HTTP as a replacement for RPC over HTTP.Starting on October 31, 2017, RPC over HTTP will no longer be a supported protocol for accessing mail data from Exchange Online. Starting on this date, the following conditions will apply:
- Microsoft will not provide support for RPC over HTTP issues (regular or custom).
- No code fixes or updates to resolve problems that are unrelated to security will be released.
1024 bits are equal to how many bytes?
1024 bits are equal to how many bytes?
- 128 bytes
- 1 byte
- 64 bytes
- 32 bytes
EXPLANATION
Conversion Definitions
The following is a list of definitions relating to conversions between bits and Bytes.
What is a bit (b)?
A bit is a unit used to measure digital storage and is based on "Binary multiples of bits". The symbol for bit is b. There are 8 bits in a Byte.What is a Byte (B)?
A Byte is a unit used to measure digital storage and is based on "Binary multiples of Bytes". The symbol for Byte is B. There are 0.125 Bytes in a bit.Conversion Formula
Let's take a closer look at the conversion formula
so that you can do these conversions yourself with a calculator or with
an old-fashioned pencil and paper.
The formula to convert from bits to Bytes is:Bytes = bits ÷ 8
Conversion Example
Next, let's look at an example showing the work and calculations that are involved in converting from bits to Bytes (b to B).
bit to Byte Conversion Example
Task: Convert 3,000 bits to Bytes (show work) Formula: bits ÷ 8 = Bytes Calculations: 3,000 bits ÷ 8 = 375 Bytes Result: 3,000 bits is equal to 375 Bytes
