The Bits and Bytes of Computer Networking Flashcards
If a computer were to perform a full DNS lookup using TCP, how many packets would have to be sent between it and all name servers?
44
Using UDP, how many packets would need to be sent to perform a full DNS look up?
8
What Transport layer protocol does DNS normally use?
UDP (User Datagram Protocol)
A DNS TTL determines what?
How long a DNS entry is allowed to be cached in the Recursive Server
What is DNS Round Robin?
A method of load balancing where multiple IP addresses are assigned to a domain name. During DNS Resolution, all IPs are shared but the order rotates in each look up to spread out traffic.
In DNS Resolution, what is an A Record used for?
To point a certain domain name at a certain IPv4 IP Address
What is a AAAA - Quad A Record?
Used to point a domain name at a certain IPv6 IP Address during DNS Resolution
What is a CNAME Record?
Canonical Name Record
Used to redirect traffic from one domain to another (Eg: microsoft.com to www.microsoft.com). Setting up a CNAME means you only need to update the IP of one domain name if it changes.
What is an MX Record?
Mail Exchange Record
Used to deliver email to the correct server
What is an SRV Record?
Service Record
Used to define the location of various specific services.
(Like how MX is for email, SRV is for many service types)
What is a TXT Record?
Text Record
Used to provide the ability to associate text with a zone. This record allows domain administrators to insert any text content into DNS records. These records are used for various purposes. One example is ownership validation: To prove you own the domain, a provider may require you to add a TXT record with a particular value to your domain.
What are the 3 main parts of a domain name?
1) Subdomain - Or Host Name, eg: www.
2) Domain - The name portion, eg: google in google.com. Stored on the Authoritative Name Server.
3) TLDs (Top Level Domains) - the final portion of the domain name, eg: .com. Stored on TLD Name Servers.
How does UDP differ from TCP when transmitting data?
TCP requires constant connection and acknowledgement for every segment of a data packet to ensure nothing is lost
UDP just sends the data to it’s destination port. No string of acknowledgement means more available bandwidth. Good for streaming videos where a few missing frames won’t matter
Cat 5, Cat 5e, and Cat 6 cables are made with increasingly strict specifications to avoid _______.
Crosstalk
What does BGP stand for?
Border Gateway Protocol
What does Modulation do when transmitting data across cables?
Modulation is a way of varying the voltage of the charge moving across a cable in a constant ‘on’ state.
What does the Physical Layer consist of?
Devices and cables, means of transmitting bits across a computer network
What are the 2 main network protocols?
-TCP (Transmission Control Protocol)
-IP (Internet Protocol)
What does UDP stand for?
User Datagram Protocol
What is Crosstalk?
When an electrical pulse on one wire is accidentally detected on another wire
When a TCP Socket sends a FIN, but the corresponding ACK from the other end hasn’t been received yet, what will it’s state be?
FIN_WAIT
What does the TCP socket state SYN_SENT mean?
A synchronization request has been sent, but the connection hasn’t been established yet. (Client side only)
When a TCP Connection is ready to be closed, a four-way handshake occurs, in order, what TCP Flags are sent?
1) FIN - I’m ready to close the connection
2) ACK - I hear you
3) FIN - I am also ready to close the connection
4) ACK - Cool, let’s stop being connected
Every time a TCP connection is established, a ____________ occurs.
Three-way handshake