As our teachings do not state Zoroaster is the connecting link between the Euphrates and the Prophets in India we cannot assert this.
(Shoghi Effendi, The Compilation of Compilations vol. I, p. 22)

Question: What is the relation of the Bahá’í teaching to the ancient Zoroastrian religion?
Answer: The religions of God have the same foundation, but the dogmas appearing later have differed. Each of the divine religions has two aspects. The first is essential. It concerns morality and development of the virtues of the human world. This aspect is common to all. It is fundamental; it is one; there is no difference, no variation in it. As regards the inculcation of morality and the development of human virtues, there is no difference whatsoever between the teachings of Zoroaster, Jesus and Bahá’u’lláh. In this they agree; they are one. The second aspect of the divine religions is nonessential. It concerns human needs and undergoes change in every cycle according to the exigency of the time. For example, in the time of Moses divorce was conformable to the needs and conditions; Moses, therefore, established it. But in the time of Christ, divorces were numerous and the cause of corruption; as they were not suitable for the time, he made divorce unlawful and likewise changed other laws. These are needs and conditions which have to do with the conduct of society; therefore, they undergo change according to the exigency of the time. Moses dwelt in the desert. As there were no penitentiaries, no means of restitution in the desert and wilderness, the laws of God were an eye for an eye, a tooth for a tooth. Could this be carried out now? If a man destroys another man’s eye, are you willing to destroy the eye of the offender? If a man’s teeth are broken or his ear cut off, will you demand a corresponding mutilation of his assailant? This would not be conformable to conditions of humanity at the present time. If a man steals, shall his hand be cut off? This punishment was just and right in the law of Moses, but it was applicable to the desert, where there were no prisons and reformatory institutions of later and higher forms of government. Today you have government and organization, a police system, a judge and trial by jury. The punishment and penalty is now different. Therefore, the nonessentials which deal with details of community are changed according to the exigency of the time and conditions. But the essential foundation of the teachings of Moses, Zoroaster, Jesus and Bahá’u’lláh is identical, is one; there is no difference whatsoever.
(‘Abdu’l-Bahá, The Promulgation of Universal Peace, p. 168-169)

Regarding the question of days referring in some cases to years, and in some cases to centuries in the Tablet to a Zoroastrian follower of the Faith: The only answer we can give people who lack the faith to accept the words of the Master as being divinely inspired interpretations of the truth, is that the language of prophecy has always in the past been veiled in meaning, and that allusions are found in all the Holy Books which cannot be accepted literally, and have not been satisfactorily interpreted until the appearance of this Revelation when, we believe, the books of the past and their mysteries have been at last unsealed. Could anybody find a more logical interpretation of this allusion in the Zoroastrian literature than that given by ‘Abdu’l-Bahá, or one which fits a coherent interpretation of religious history as well as the Master’s words do?
(Shoghi Effendi, The Compilation of Compilations vol. I, p. 22)

Thou hadst written that in the sacred books of the followers of Zoroaster it is written that in the latter days, in three separate Dispensations, the sun must needs be brought to a standstill. In the first Dispensation, it is predicted, the sun will remain motionless for ten days; in the second for twice that time; in the third for no less than one whole month. The interpretation of this prophecy is this: the first Dispensation to which it refers is the Muhammadan Dispensation during which the Sun of Truth stood still or ten days. Each day is reckoned as one century. The Muhammadan Dispensation must have, therefore, lasted no less than one thousand years, which is precisely the period that has elapsed from the setting of the Star of the Imamate to the advent of the Dispensation proclaimed by the Báb. The second Dispensation referred to in this prophecy is the one inaugurated by the Báb Himself which began in the year 1260 A.H. and was brought to a close in the year 1280 A.H. As to the third Dispensation—the Revelation proclaimed by Bahá’u’lláh—inasmuch as the Sun of Truth when attaining that station shineth in the plenitude of its meridian splendor its duration hath been fixed for a period of one whole month, which is the maximum time taken by the sun to pass through a sign of the Zodiac. From this thou canst imagine the magnitude of the Bahá’í cycle—a cycle that must extend over a period of at least five hundred thousand years.
(Shoghi Effendi, The World Order of Bahá’u’lláh: Selected Letters, p. 101-2)

To His Dispensation the sacred books of the followers of Zoroaster had referred as that in which the sun must needs be brought to a standstill for no less than one whole month. To Him Zoroaster must have alluded when, according to tradition, He foretold that a period of three thousand years of conflict and contention must needs precede the advent of the World-Savior Shah-Bahram, Who would triumph over Ahriman and usher in an era of blessedness and peace.
(Shoghi Effendi, God Passes By, p. 94-95)

What we can be sure of is that when Bahá’u’lláh or the Master stated that Zoroaster foretold a Promised One’s coming, it is correct. The Zoroastrians have no way of contradicting this assertion of ours, as they themselves know their scriptures are not in the original form, and therefore not absolutely authentic.
(Shoghi Effendi, The Compilation of Compilations vol. I, p. 21)

Zoroaster lived about a thousand years before Christ. There is no exact date in the teachings regarding the beginning of His Dispensation. The personages in Zenda- Avesta cannot be absolutely relied upon, as the Avesta is not to be regarded as the authentic compilation of the writings of the Prophet.
(Shoghi Effendi, The Compilation of Compilations vol. I, p. 21)