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IPV4 Addressing

Subject : it-skills

Instructions:

Answer 50 questions in 15 minutes.
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Match each statement with the correct term.
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This is a study tool. The 3 wrong answers for each question are randomly chosen from answers to other questions. So, you might find at times the answers obvious, but you will see it re-enforces your understanding as you take the test each time.

1. What is the first octet rule for IPv4 address classes in decimal?
Class A 1-126; Class B 128-191; Class C 192-223; Class D 224-239; Class E 240-254
Reset
Internet Protocol
Length of header in words (32-bit)

2. What is prefix /28 in decimal notation?
255.255.255.240
192.88.99.0/24
Number of octets - starting with the octet indicated by the Acknowledgement Number - that the receiver will accept from the sender before the sender must stop transmitting and wait for a new Acknowledgement
NIRs

3. What is a TCP Acknowledgement Number?
255.255.255.128
RFC 791
The next sequence number that the source expects to receive from the destination
Identifier; Flags and Fragmentation Offset

4. What is IP?
127.0.0.0/8
Padding of zeros to ensure that the header ends on a 32-bit boundary
Internet Protocol
1

5. Which IPv4 address range is reserved for benchmark testing of Internet devices (RFC 2544)?
Mostly large ISPs - enterprises - or academic institutions
8
198.18.0.0/15
0

6. What TCP/IP protocol suite layer corresponds to the physical and data link layers of the OSI model?
Type (8-bit); Code (8-bit); Checksum (16-bit); Variable fields
Network interface
Class A 0; Class B 10; Class C 110; Class D 1110; Class E 1111
IANA

7. Configures how long a dynamically learned protocol address and its corresponding hardware address remains in the ARP cache
Congestion Window Reduced
Minimize Delay (1-bit); Maximise Throughput (1-bit); Maximise Reliability (1-bit); Minimize Monetary Cost (1-bit)
Time Exceeded
Router(config-if)#arp timeout {seconds}

8. What is the IPv4 Protocol number for OSPF?
89
Per-Hop Behaviour (PHB)
ICANN and IANA
Redirect

9. What routing protocols are classful?
Data Offset
Largest segment size that the sender is willing to accept
Router(config)#arp {ip-address} {mac-address} arpa
RIPv1 and IGRP

10. Who owns the processes by which public IP address space and AS numbers are allocated and assigned?
Offset - in units of eight octets - from the beginning of the original header to the beginning of the fragment
1
ICANN
Used by a host to obtain the IPv4 address associated with its own MAC address

11. Who is responsible for the global coordination of the DNS Root - IP addressing - and other Internet protocol resources?
Loose source routing; Strict source routing; Record route; Timestamp
IANA
198.18.0.0/15
4

12. What is added after the Option field in the TCP header?
Congestion Window Reduced
RIRs
Sequence Number + Data payload octets + 1
Padding of zeros to ensure that the header ends on a 32-bit boundary

13. What is SYN?
46
Sequence Number + Data payload octets + 1
Offset - in units of eight octets - from the beginning of the original header to the beginning of the fragment
Synchronize

14. What is ICANN?
IANA
Duplicate address checks; Advertise new data-link identifiers; Update the ARP caches of hosts
Internet Corporation for Assigned Network Numbers
9

15. Which IPv4 address range is reserved for self-identification on a local subnet?
Data Offset
Protocols that include subnet masks in their routing updates
Router(config-if)#arp timeout {seconds}
0.0.0.0/8

16. What is the format of the TCP Header Length field?
Both the TCP header and the encapsulated data
Hardware type (16-bit); Protocol type (16-bit); Hardware address length (8-bit); Protocol address length (8-bit); Operation (16-bit); Sender hardware address; Sender protocol address; Target hardware address; Target protocol address
Acknowledgements - checksums and timers
Length of header in words (32-bit)

17. How can the receiver determine the size of a packet's data payload based on the IPv4 header?
Subtract Header Length field from Total Length field
Internet Corporation for Assigned Network Numbers
Largest segment size that the sender is willing to accept
Version (4-bit); Header Length (4-bit); ToS (8-bit); Total Length (16-bit); Identifier (16-bit); Flags (3-bit); Fragment Offset (13-bit); TTL (8-bit); Protocol (8-bit); Header Checksum (16-bit); Source Address (32-bit); Destination Address (32-bit);

18. What is the function of ICMP redirect messages?
They are the same byte - but the names and value interpretations are different
IANA
Used by routers to notify hosts of another router on the data link that should be used for a particular destination
10.0.0.0/8; 172.16.0.0/12; 192.168.0.0/16

19. What is ICMP Type 0?
255.255.255.224
6
Protocols that don't include subnet masks in their routing updates
Echo Reply

20. What is prefix /27 in decimal notation?
255.255.255.224
88
6
Internet Corporation for Assigned Network Numbers

21. What is ICMP Type 8?
Used by a host to obtain the IPv4 address associated with its own MAC address
ICANN and IANA
8
Echo

22. What field identifies where the TCP encapsulated data fits within the data stream from the sender?
Socket
Sequence Number
88
0 Routine; 1 Priority; 2 Immediate; 3 Flash; 4 Flash Override; 5 Critical; 6 Internetwork Control; 7 Network Control

23. Which IPv4 address range is reserved for IPv6 to IPv4 (6to4) relays (RFC 3068)?
Internet Protocol
Acknowledgements - checksums and timers
192.88.99.0/24
6

24. What is the format of the DiffServ byte?
Destination Unreachable
DSCP (6-bit); ECN (2-bit)
20 octets
Sequence Numbers

25. What is the prerequisite for using the Urgent Pointer field in the TCP header?
URG flag set
89
RFC 3330
Mostly large ISPs - enterprises - or academic institutions

26. What are the private IPv4 address ranges?
10.0.0.0/8; 172.16.0.0/12; 192.168.0.0/16
2
LIRs
Address Resolution Protocol

27. What is the TTL field in the IPv4 header?
Router(config-if)#no ip redirects
Echo Reply
Application
Time to Live

28. What is the IPv4 Protocol number for IP in IP encapsulation?
Source Port (16-bit); Destination Port (16-bit); Sequence Number (32-bit); Acknowledgement Number (32-bit); Header Length (4-bit); Reserved (4-bit); Flags (8-bit); Windows Size (16-bit); Checksum (16-bit); Urgent Pointer (16-bit); Options; Padding
Internet Protocol
Each router decrements the TTL
4

29. What are the most frequently used options in the IPv4 header?
NIRs
Loose source routing; Strict source routing; Record route; Timestamp
RIPv1 and IGRP
Used by a host to obtain the IP address associated with another host's MAC address

30. What is prefix /26 in decimal notation?
Push
Host-to-host
255.255.255.192
60 octets

31. What is the ARP Hardware type value for Ethernet?
Uniquely identify every application in the network
17
10.0.0.0/8; 172.16.0.0/12; 192.168.0.0/16
1

32. What is gratuitous ARP?
DSCP (6-bit); ECN (2-bit)
Mostly large ISPs - enterprises - or academic institutions
An ARP request issued by a host with its own IPv4 address as the target address
Internet Corporation for Assigned Network Numbers

33. What is the format of a UDP header?
10.0.0.0/8; 172.16.0.0/12; 192.168.0.0/16
Loose source routing; Strict source routing; Record route; Timestamp
Source Port (16-bit); Destination Port (16-bit); UDP Length (16-bit); Checksum (16-bit)
IANA

34. What is the content of the TCP Window Size field?
Padding of zeros to ensure that the header ends on a 32-bit boundary
Number of octets to be added to the Sequence Number to indicate the end of the urgent data
ECN-Echo
Number of octets - starting with the octet indicated by the Acknowledgement Number - that the receiver will accept from the sender before the sender must stop transmitting and wait for a new Acknowledgement

35. What is the ARP Protocol address length value for IPv4?
89
4
255.255.255.240
Socket

36. What is the IPv4 protocol number for UDP?
3
DSCP (6-bit); ECN (2-bit)
17
Router Advertisement

37. What is a TCP port number of an application called when it is coupled with the IP address of the server?
47
Congestion Window Reduced
Socket
Internet Assigned Numbers Authority

38. What is the ARP Hardware address length value for Ethernet?
Number of octets to be added to the Sequence Number to indicate the end of the urgent data
6
Maximum Segment Size (MSS)
Router#clear arp-cache [{interface {interface}} | {ip-address}]

39. What is NIR?
Redirect
20 octets
255.255.255.192
National Internet Registry

40. What is prefix /25 in decimal notation?
More Fragments follow
0.0.0.0/8
All Internet Registries
255.255.255.128

41. What is added after the option field in the IPv4 header?
Router(config-if)#arp timeout {seconds}
Each router decrements the TTL
Padding of zeros to ensure that the header ends on a 32-bit boundary
Time to Live

42. What is the IPv4 Protocol number for IGMP?
The next sequence number that the source expects to receive from the destination
Padding of zeros to ensure that the header ends on a 32-bit boundary
6
2

43. What is prefix /30 in decimal notation?
Router#clear arp-cache [{interface {interface}} | {ip-address}]
255.255.255.252
IANA
255.255.255.240

44. Who allocates IP address space and AS numbers to RIRs?
IANA
255.255.255.224
Network interface
Final

45. Adds a permanent static ARP entry for an Ethernet host
Identifier; Flags and Fragmentation Offset
1
Duplicate address checks; Advertise new data-link identifiers; Update the ARP caches of hosts
Router(config)#arp {ip-address} {mac-address} arpa

46. What is the format of the Flags field in the IPv4 header?
255.255.255.128
Router(config-if)#no ip redirects
Reserved (1-bit); DF (1-bit); MF (1-bit)
National Internet Registry

47. What is Reverse ARP?
255.255.255.240
1-2 Network interface; 3 Internet; 4 Host-to-host; 5-7 Application
Used by a host to obtain the IPv4 address associated with its own MAC address
Redirect

48. Which RFC defines the special use IPv4 address ranges?
0
Internet
Class A 0; Class B 10; Class C 110; Class D 1110; Class E 1111
RFC 3330

49. What is ECE?
Internet Protocol
Version (4-bit); Header Length (4-bit); ToS (8-bit); Total Length (16-bit); Identifier (16-bit); Flags (3-bit); Fragment Offset (13-bit); TTL (8-bit); Protocol (8-bit); Header Checksum (16-bit); Source Address (32-bit); Destination Address (32-bit);
ECN-Echo
Destination Unreachable

50. What is the function of ICMP router advertisement and router selection messages?
17
Acknowledgements - checksums and timers
Used by IRDP on some operating systems to discover local routers
255.255.255.248