1.1 Network theory _ IPv4/IPv6
Which layer checksum run on IPv4 and IPv6?
*For IPv4* there are header checksum (Layer3) and UDP checksum (Layer4_Optional). *For IPv6* there is mandatory UDP checksum in Layer4 (Transport Layer)
In IPv6 Path MTU Discovery, which ICMP message is sent by an intermediary router that requires a smaller MTU?
*Packet Too Big*. Wrong answers= Time Exceeded, with code 1: If a router receives a packet with a Hop Limit of zero, or if a router decrements a packet's Hop Limit to zero, it MUST discard the packet and originate an ICMPv6 Time Exceeded message with Code 0 to the source of the packet. This indicates either a routing loop or too small an initial Hop Limit value. / Destination Unreachable: generated by a router, or by the IPv6 layer in the originating node, in response to a packet that cannot be delivered to its destination address for reasons other than congestion. / Multicast Termination Router:used to expedite the notification of a change in the status of a router's multicast forwarding functions
Which three options are sub-subfields of the IPv4 Option Type subfield?
- Option Class - Copied - Option Number
Which two statements about packet fragmentation on an IPv6 network are true? - The fragment header is ... bits long. - The identification field is ... bits long.
- The *fragment header is 64 bits* long. (32b Fragment Data + 32b Identification) - The identification field is 32 bits long.
What is the minimum link MTU value for IPv6?
1280 bytes
Which three fields are present in the IPv6 header? A.Next Header B.Traffic Class C.Options D.Time to Live E.Flags F.Flow Label
A,B,F Wrong answers: Options: is for extension IPv6 header. / Time to Live: that is for IPv4. in IPv6 is Hop Limit. / Flags: this is used or fragmentation IPv6 header.
The fixed header of an IPv6 packet can be fragmented?
Absolutely not!
An IPv4 host can drop any fragments larger than ... bytes.
An IPv4 host can drop any fragments larger than 576 bytes.
An IPv6 host can drop any fragments larger than ... bytes.
An IPv6 host can drop any fragments larger than 1280 bytes.
Which two options are valid IPV6 extension header types? A. Flow Label B. Encapsulating security Payload C. Version D. Traffic Class E. Mobility
BE Wrong answers: Flow Label, Version and Traffic Class are in IPv6 fixed header format.
IPv6 extension header ESP / Fragment / AH / Destination / Hop-by-Hop
ESP: Carries encrypted data / Fragment: Specifies the parameters used to split datagrams/ AH: Carries authentication information / Destination: Specifies options to be examined only at the final device / Hop-by-Hop: Specifies options to be examined by all devices.
In IPv4, hosts perform fragmentation?
No, In IPv6, only hosts perform fragmentation. IPv4 routers do perform fragmentation. *IPv6 routers do NOT perform fragmentation*.
IPv6 uses a UDP checksum to verify packet integrity?
Yes. The Checksum field in the UDP packet is mandatory with IPv6. This was optional in IPv4.
What is the maximum number of secondary IP addresses that can be configured on a router interface?
no limit to the number of addresses
