Exam 350-401 topic 1 question 452 discussion

From the OCG page 368: "The following traffic descriptors are typically used for classification: ■ Internal: QoS groups (locally significant to a router) ■ Layer 1: Physical interface, subinterface, or port ■ Layer 2: MAC address and 802.1Q/p Class of Service (CoS) bits ■ Layer 2.5: MPLS Experimental (EXP) bits ■ Layer 3: Differentiated Services Code Points (DSCP), IP Precedence (IPP), and source/ destination IP address ■ Layer 4: TCP or UDP ports ■ Layer 7: Next Generation Network-Based Application Recognition (NBAR2)". A and B are correct.

https://study-ccna.com/qos-classification-marking/

A & B are correct DSCP is an advancement over the earlier Type of Service (ToS) field in the IP header. https://webhostinggeeks.com/blog/what-is-differentiated-services-code-point-dscp/#:~:text=DSCP%20is%20an%20advancement%20over%20the%20earlier%20Type%20of%20Service%20(ToS)%20field%20in%20the%20IP%20header.

A B and E should be correct. if I had to chose only 2 I will go with A and E

The ToS byte in the IP header contains DSCP info, but it's DSCP that actually describes precedence/drop priority

This one seems to be badly worded... or it should specify 3 answers. A,B, and E

By Chatgpt:- The two parameters that are examples of a QoS traffic descriptor are: A. DSCP (Differentiated Services Code Point), which is a field in the IP header that specifies the level of service for a particular packet. D. Bandwidth, which is the amount of data that can be transmitted over a network in a given period of time. Note: MPLS EXP bits and ToS (Type of Service) are also related to QoS but are not traffic descriptors themselves. The MPLS EXP bits are used to specify the priority of MPLS packets, while ToS is an older field in the IP header that has been replaced by DSCP. Packet size is not a QoS traffic descriptor but can be used in QoS policies to limit the amount of bandwidth that a certain type of traffic can use.

https://www.cisco.com/c/en/us/td/docs/routers/ncs4000/software/qos/configuration_guide/b-qos-cg/b-qos-cg_chapter_0101.pdf Traffic Descriptors from this question are A and E per the link above.

(ToS) and (DSCP) both of them are parameter that used to mark traffic with a specific value, indicating its priority level. while MPLS EXP bits is a parameter that is a part of (QoS) traffic descriptor. The MPLS EXP bits are 3-bit fields in the MPLS label header that can be used to indicate the level of priority of the packet and MPLS Experimental (EXP) bits is the descriptor for classification Layer 2.5

provided answer true

The ToS bit could also a descriptor for QoS as it is used to classify packets for QoS treatment by routers

The MPLS experimental bits (EXP) field is a 3-bit field in the MPLS header that you can use to define the QoS treatment (per-hop behavior) that a node should give to a packet. In an IP network, the DiffServ Code Point (DSCP) (a 6-bit field) defines a class and drop precedence.

A, B is the answer