Question:
In which three ways is an IPv6 header simpler than an IPv4 header? (Choose three)
- Unlike IPv4 headers, IPv6 headers have a fixed length.
- IPv6 uses an extension header instead of the IPv4 Fragmentation field.
- IPv6 headers eliminate the IPv4 Checksum field.
- IPv6 headers use the Fragment Offset field in place of the IPv4 Fragmentation field.
- IPv6 headers use a smaller Option field size than IPv4 headers.
- IPv6 headers use a 4-bit TTL field, and IPv4 headers use an 8-bit TTL field.
Explanation:
The IPv4 and IPv6 headers are shown below for your comparison:
[caption id="attachment_21762" align="aligncenter" width="500"]
IPv6 Header fields[/caption]
IPv6 eliminates the Header Checksum field, which handles error checking in IPv4. IPv6 depends on reliable transmission in the data link protocols and on error checking in upper-layer protocols instead -> Answer C is correct.
While IPv4 header’s total length comprises a minimum of 20 octets (8 bits per octet), IPv6 header has only 8 fields with a fixed length of 40 octets -> Answer A is correct.
| IPv4 header does not have a fixed length because of the Options fields. This field is used to convey additional information on the packet or on the way it should be processed. Routers, unless instructed otherwise, must process the Options in the IPv4 header. The processing of most header options pushes the packet into the slow path leading to a forwarding performance hit. |
IPv4 Options perform a very important role in the IP protocol operation therefore the capability had to be preserved in IPv6. However, the impact of IPv4 Options on performance was taken into consideration in the development of IPv6. The functionality of Options is removed from the main header and implemented through a set of additional headers called extension headers. The “Next Header” field in IPv6 can be used to point to the extension headers.
Reference: Click Here
Exam with this question: CCNA v3.0 (200-125) Study Guide – Exam Dumps
Please login or Register to submit your answer