Week 9: Layer 7 Fundamentals

Question 1

Name 2 of the four HTTP safe methods .(Safe means that it does not modify the web server)

Answer 1

a. Head - retrieves data from headers
b. Get - retrieves data from page
c. Options - retrieves HTTP methods form server
d. Trace - Echo to detect if any changes are being made in route

Question 2

What makes them safe?

Answer 2

Info retrieval does not change the server

Question 3

Why would you use TLS (Transport Layer Security) for communication between two hosts?

Answer 3

a. Information is encrypted and secure
b. Prevent eavesdropping and tampering
c. Does checks to make sure that packet has not changed
d. Rides on TCP

Question 4

What protocol and port does NTP use ?

Answer 4

a. UDP

b. Port 123

Question 5

What is calculated when NTP syncs with remote server?

Answer 5

a. Round trip delay time

b. Off-set

Question 6

Layer 4 protocols to transport to SIP - Session Initiation Protocol or Signaling Protocol

Answer 6

a. TCP - for people who know what they are doing
b. UDP - supported by all
c. SCTP

Question 7

Can you list three SIP request methods?

Answer 7

a. Register
b. Invite
c. Ack
d. Cancel
e. Bye
f. Options

Question 8

What protocol and port does SMTP use?

Answer 8

TCP; Port 25

Question 9

What three command reply sequences comprise a SMTP message?

Answer 9

a. Mail
b. Receipt - RCTP
c. Data

Question 10

Why use SNMP?

Answer 10

Manage devices on network

Question 11

List 3 of 7 SNMP PDU types

Answer 11

a. Can use to push configs to devices - security risk!
b. Get
c. Set
d. Get Next
e. Get Bulk
f. Response
g. Trap
h. Inform

Question 12

Major Enhancement of SNMP V3

Answer 12

a. Community string with username and password
b. Remote enhancements
c. Optional encryption

Question 13

What protocol and port for SSH

Answer 13

TCP; Port 22

Question 14

Name a method for securely copying files via SSH tunnels?

Answer 14

a. SCP - Secure copy Protocol uses SSH to copy files
b. Rsync -
c. SFTP - SSH file transfer
d. FISH -Files transferred of Shell Protocol

Question 15

What protocol and port does telnet use?

Answer 15

TCP; Port 23

Question 16

Drawback using telnet

Answer 16

Not secure - unencrypted

Question 17

What does AAA stand for?

Answer 17

Authentication, Authorization, & Accounting

Question 18

Protocol and ports for FTP

Answer 18

a. TCP

b. 20 & 21 - 21 is the port you connect to; 20 sends the data back

Question 19

Why use FTP passive mode- Google this one!!

Answer 19

a. FTP passive mode - use when the client is behind firewall

b. Passive makes it so that data is send back on port 21 - allows return traffic

Question 20

Protocol and ports for DHCP

Answer 20

UDP; Ports 67 and 68

Question 21

List 2 of 4 phases of DHCP process

Answer 21

a. Discover
b. Offer
c. Request
d. Acknowledge

Question 22

What is RTP used for?

Answer 22

Voice and audio media - streaming

Question 23

Initial DHCP request sent?

Answer 23

Broadcast

Question 24

DNS port and protocol

Answer 24

UDP; Port 53

Question 25

What is authoritative name Server?

Answer 25

a. Other servers check in with the auth server
b. DNS records have TTL and are cached across the internet
c. Authoratative servers are the source for a zone
d. Public DNS Changes can take hours to deploy across the internet
e. Keep this in mind for cut-over plans

Question 26

DNS is everything - the entire structure of the internet

Answer 26

a. There are many applications that depend on DNS

b. Certificate Checks use DNS

Question 27

MEMORIZE COMMON PORTS - Used for ACLs,

Answer 27

Machine generated alternative text: Protocols to BlocklUnblock
 1. ICMP - Pings
 a. Echo
 b. Echo Reply
 2. TCP
 a. 21-FTP
 b. 22-SSH
 c. 23-Telnet
 d. 25-SMTP
 e. 53-DNS Server
 f. 80-HTTP
 g. 11O-POP3
 h. 143-IMAP4
 I. 443 - HTTPS
 3. UDP
 a. 53-DNS Client
 b. 69-TFTP
 c. 67 - 68 DHCP
 4. IP
 a. Jl encompassing protocols